JPWO2007058294A1 - Encoding apparatus and method, decoding apparatus and method, and transmission system - Google Patents

Abstract

The present invention relates to an encoding device and method, a decoding device and method, and a transmission system that enable image data sent after being compressed and encoded to be output as a decoded image in a shorter time on the receiving side. At the time of wavelet transform, filter processing is performed on a line-by-line basis, with the number of lines in which weighing data for one line of the lowest frequency component is generated as a unit. The first processing is performed from the first line to the seventh line, and when the decomposition level = 1, the coefficients C1, C2, and C3 of the high frequency component, and the coefficients Ca, coefficient Cb, and coefficient Cc of the low frequency component are obtained. The high frequency component coefficient C4 and the low frequency component coefficient C5 are generated from the coefficient Ca, the coefficient Cb, and the coefficient Cc at the decomposition level = 2. These coefficients are rearranged in the order from low to high and supplied to the synthesis filter. The synthesis filter generates and outputs image data by performing filter processing of the coefficients in the order of supply.

Description

  The present invention relates to an encoding apparatus and method, a decoding apparatus and method, and a transmission system, and in particular, a code that enables image data transmitted after compression encoding to be output as a decoded image in a shorter time on the receiving side. The present invention relates to an encoding apparatus and method, a decoding apparatus and method, and a transmission system.

  Conventionally, a technique called JPEG (Joint Photographic Experts Group) standardized by ISO (International Organization for Standardization) has been widely used as a compression encoding method for image data. This JPEG method divides image data into blocks, applies DCT (Discrete Cosine Transform) to each of the divided areas to obtain DCT coefficients, quantizes the obtained DCT coefficients, and further performs entropy coding. By doing so, high quality and high compression rate are realized.

  In recent years, active research has been conducted on a coding method in which image data is divided into a plurality of bands using a filter bank, which is a combination of a high-pass filter and a low-pass filter, and coding is performed for each divided band. It has become. Among such encoding methods, an encoding method called wavelet transform encoding does not cause block distortion at the time of high compression, which is a problem in the above-described DCT. It is regarded as a promising new technology that can be used in place of DCT.

  For example, JPEG2000, whose international standardization was completed in January 2001, employs a compression coding method that combines this wavelet transform with bit modeling in bit plane units and high-efficiency entropy coding using arithmetic coding. According to the JPEG2000 system, a significant improvement in coding efficiency is realized over the conventional JPEG system. Patent Document 1 describes a wavelet transform method that further improves encoding efficiency.

In such an international standard, only the standard on the decoder side is defined, and the encoder side can be designed freely.

  By the way, in the above-described JPEG2000 system, for example, conventionally, necessary header information cannot be described unless encoding of all the pixels in the screen is completed due to the algorithm. In other words, in this header information, it is necessary to describe information that is essential at the time of decoding, such as the compressed data size of the encoding result, or a marker must be added to the end of the encoded data. It is not decided until after all the encoding for the screen is completed.

  This is not limited to the JPEG2000 system, and the same applies to the JPEG system and the MPEG (Moving Pictures Experts Group) system, which is a moving image data compression system.

  For this reason, according to the conventional image compression technique, the output of the encoded code stream as a result of compression encoding is performed after encoding all the images for one frame or one field in the case of interlaced images. There was a problem that had to be done.

  As a result, there has been a problem that it has not been possible to prevent a delay time corresponding to one frame or one field in the case of an interlaced image between the image data transmission side and the reception side.

  Accordingly, an object of the present invention is to provide an encoding apparatus and method, a decoding apparatus and method, and a decoding apparatus and method capable of performing compression encoding and decoding of image data and outputting decoded image data with lower delay, and It is to provide a transmission system.

  An encoding apparatus according to a first aspect of the present invention is an encoding apparatus that encodes image data, performs a filtering process on the image data in a hierarchical manner, and uses coefficient data decomposed for each frequency band. Filter means for generating a plurality of subbands, storage means for storing the coefficient data generated by the filter means in an accumulative manner, and outputting the coefficient data stored by the storage means in a predetermined order Coefficient rearranging means for rearranging.

  The filter means can perform the filtering process in units of lines from the upper end side to the lower end side of the screen.

  The filter means may perform a filtering process on the image data for each line block that is image data for the number of lines necessary to generate at least one line of coefficient data of a subband of the lowest frequency component. it can.

  The filter means can perform the filtering process in both a vertical direction and a horizontal direction of a screen corresponding to the image data.

  At least one of the number of taps and the number of decomposition levels of the filter processing by the filter means can be determined according to a target delay time.

  The filter means can perform wavelet filter processing that further performs the filter processing on low-band component subband coefficient data obtained by the filtering processing.

  The filter means can perform the wavelet filter processing using a lifting technique.

  The filtering means, when performing the filtering process of the decomposition level = X + 1 using the lifting technique, is performed on the coefficient data calculated as the subband of the low frequency component by the filtering process of the decomposition level = X Can do.

  The storage means is a first buffer means for holding low-band component subband coefficient data generated in the course of the wavelet filter processing by the filter means, and is generated in the course of the wavelet filter processing by the filter means. And a second buffer means for holding coefficient data of the subband of the high frequency component to be processed.

  The second buffer means can hold the subband coefficient data of the band component other than the lowest band until the filter means generates the subband coefficient data of the lowest band component.

  The coefficient rearranging means can rearrange the coefficient data so that the subbands are output in the order of low frequency components to high frequency components.

  The coefficient rearranging means rearranges the image data for each line block that is image data corresponding to the number of lines necessary to generate coefficient data for at least one line of the subband of the lowest frequency component. be able to.

  An entropy encoding means for entropy encoding the coefficient data may be further provided.

  The entropy encoding unit can sequentially entropy encode the coefficient data rearranged by the coefficient rearranging unit.

  The coefficient rearranging means rearranges the coefficient data so that the subbands are output in order from a low frequency component to a high frequency component, and the entropy encoding means performs the coefficient data by the coefficient rearranging means. As soon as is rearranged, the reordered coefficient data can be entropy-coded in the order of low-frequency components to high-frequency components.

  The entropy encoding unit performs entropy encoding on the coefficient data generated by the filter unit, and the storage unit stores the coefficient data entropy encoded by the entropy encoding unit. it can.

  The storage means is generated as subbands of band components other than the lowest band component until the coefficient data of the subband of the lowest band component is entropy coded by the entropy coding means, and the entropy coding means performs entropy coding. The encoded coefficient data can be stored.

  The coefficient rearranging means rearranges the coefficient data entropy-encoded by the entropy encoding means stored in the storage means so as to output the subbands in the order of low-frequency components to high-frequency components. As soon as the coefficient data is rearranged, the rearranged coefficient data can be output in the order of low frequency components to high frequency components.

  The entropy encoding unit can entropy encode the coefficient data of a plurality of lines in the same subband together.

  The entropy encoding means includes all sub-blocks constituting a line block that is a coefficient data group corresponding to image data for the number of lines necessary to generate coefficient data for one line of at least the subband of the lowest frequency component. Coding can be performed on a coefficient data string in which band lines are arranged in a one-dimensional direction in the order from low to high.

  The entropy encoding means includes a quantization means for quantizing the coefficient data generated by the filter means, and a coefficient of a quantization result obtained by quantizing the coefficient data by the quantization means as an information source Information source encoding means for encoding.

  Coefficient data for each line block, which is a set of coefficient data corresponding to image data for the number of lines required to generate coefficient data for one line of at least the subband of the lowest band component, is the entropy encoding means. Packetizing means for adding a predetermined header to the encoding result data obtained by entropy encoding in the order of low frequency components to high frequency components, and packetizing the header and the data body; and Sending means for sending the packet generated by the processing, wherein the entropy coding means, the packetizing means, and the sending means perform each processing simultaneously and in parallel, and the entropy coding means The entropy encoding of the coefficient data is performed on a block basis, and the packetizing means is adapted to generate an error by the entropy encoding means. As soon as the encoding result data for each line block is generated by entropy encoding, the encoding result data for each line block is packetized, and the sending means encodes the line block by the packetizing means. As soon as the resulting data is packetized, the resulting packet can be sent out.

  In the header, identification information for identifying the line block in the screen, a data length of the data body, and encoding information can be recorded.

  The entropy encoding means includes a quantization means for quantizing the coefficient data generated by the filter means, and a coefficient of a quantization result obtained by quantizing the coefficient data by the quantization means as an information source Information source encoding means for encoding, and the encoded information may include information on a quantization step size of quantization performed by the quantization means.

  The quantization step size information may include quantization step size information for every subband.

  An encoding method according to a first aspect of the present invention is an encoding method of an encoding device that encodes image data, wherein the image data is hierarchically filtered and decomposed for each frequency band. A filter step for generating a plurality of subbands composed of the coefficient data, a storage control step for accumulatively storing the coefficient data generated by the processing of the filter step in a storage unit, and control by the processing of the storage control step And a coefficient rearranging step for rearranging the coefficient data stored in the storage unit so as to be output in a predetermined order.

  A decoding device according to a second aspect of the present invention is a decoding device that decodes encoded data obtained by encoding image data, the first hierarchically supplied to the image data supplied in line units. Storage means for storing coefficient data of a plurality of subbands that have been subjected to filter processing and decomposed for each frequency band, and coefficient rearrangement for rearranging the coefficient data stored in the storage means so as to be output in a predetermined order And a second filtering process on the coefficient data rearranged by the rearranging means and output from the storage means, and synthesizes coefficient data of a plurality of subbands decomposed into frequency bands. Filter means for generating the image data.

  The coefficient rearranging means can rearrange the coefficient data so that the subbands are output in the order of low frequency components to high frequency components.

  The coefficient rearranging means converts the coefficient data stored in the storage means into image data corresponding to the number of lines necessary to generate coefficient data for at least one line of the subband of the lowest frequency component. Rearrangement can be performed for each line block which is a set of the corresponding coefficient data.

  The filter means can generate the image data by performing the second filter processing in units of lines from the upper end side to the lower end side of the screen.

  The filter means is a line that is a set of coefficient data corresponding to image data corresponding to the number of lines necessary to generate at least one line of coefficient data for the subband of the lowest frequency component for the coefficient data. The second filtering process can be performed for each block.

  The filter means can perform the second filter process using a lifting technique.

  An entropy decoding unit that performs entropy decoding of the encoded data in units of lines for each subband is further provided, and the storage unit can store coefficient data obtained by entropy decoding by the entropy decoding unit.

  The entropy decoding means includes all subbands constituting a line block that is a coefficient data group corresponding to image data corresponding to the number of lines necessary to generate coefficient data for one line of at least one subband of the lowest frequency component. The encoded data in which the lines are encoded and arranged in one dimension can be decoded.

  The entropy decoding means includes information source decoding means for performing information source decoding on the encoded data, and inverse quantization means for inversely quantizing coefficient data obtained as a result of information source decoding by the information source decoding means; Can be provided.

  A decoding method according to a second aspect of the present invention is a decoding method of a decoding device that decodes encoded data obtained by encoding image data, and is hierarchically applied to the image data supplied in line units. A storage control step for storing in the storage unit coefficient data of a plurality of subbands that has been subjected to the first filter processing and decomposed for each frequency band, and a coefficient that is controlled by the processing of the storage control step and stored in the storage unit A coefficient rearrangement step for rearranging the data so as to output the data in a predetermined order, a second filter process is performed on the coefficient data rearranged by the processing of the rearrangement step and output from the storage unit, and the frequency A filter step of generating image data by combining coefficient data of a plurality of subbands decomposed into bands.

  A transmission system according to a third aspect of the present invention includes: an encoding device that encodes image data; and a decoding device that decodes encoded data obtained by encoding the image data. The encoding device and the decoding device A transmission system for transmitting the encoded data between the encoding devices, wherein the encoding device performs a first filter process on the image data hierarchically and includes coefficient data decomposed for each frequency band First filter means for generating a plurality of subbands, storage means for storing the coefficient data generated by the first filter means in an accumulative manner, and the coefficient data stored by the storage means for a predetermined value Coefficient rearranging means for rearranging so as to output in order, and the decoding device is rearranged by the coefficient rearranging means transmitted from the encoding device via a transmission path. Second filter means for performing a second filtering process on the coefficient data and synthesizing coefficient data of a plurality of subbands decomposed into frequency bands to generate image data.

  In the first aspect of the present invention, image data is hierarchically filtered to generate a plurality of subbands composed of coefficient data decomposed for each frequency band, and the generated coefficient data is The stored coefficient data is rearranged so that the stored coefficient data is output in a predetermined order.

  In the second aspect of the present invention, the coefficient data of a plurality of subbands that are supplied in units of lines and subjected to hierarchical first filter processing on image data and decomposed for each frequency band are stored, The stored coefficient data is rearranged so as to be output in a predetermined order, the second filter processing is performed on the rearranged output coefficient data, and a plurality of parts are divided into frequency bands. The subband coefficient data are combined to generate image data.

  In the third aspect of the present invention, in the encoding device, the first filter processing is hierarchically performed on the image data, and a plurality of subbands composed of coefficient data decomposed for each frequency band are generated. The generated coefficient data is stored accumulatively, rearranged so that the stored coefficient data is output in a predetermined order, and transmitted from the encoding device via the transmission path in the decoding device. The second filter processing is performed on the coefficient data rearranged in a predetermined order, and the plurality of subband coefficient data decomposed into frequency bands are combined to generate image data.

  In the present invention, image data is filtered hierarchically to generate a plurality of subbands composed of coefficient data decomposed for each frequency band, and the coefficient data generated by the filter processing is accumulated in the storage unit. Since the coefficient data stored in the storage unit is rearranged so that the coefficient data is output in a predetermined order, the coefficient data can be processed in the supplied order at the time of decoding. There is an effect that the delay time from encoding to decoding of encoded data and outputting of image data can be shortened.

It is a block diagram which shows the structure of an example of the image coding apparatus to which this invention is applied. It is an approximate line figure for explaining wavelet transform roughly. It is an approximate line figure for explaining wavelet transform roughly. It is a basic diagram for demonstrating roughly the wavelet transformation at the time of applying a lifting technique with respect to a 5x3 filter. It is a basic diagram for demonstrating roughly the wavelet inverse transformation at the time of applying a lifting technique with respect to a 5x3 filter. It is a basic diagram which shows the example which performed filtering by lifting of 5x3 filter to decomposition | disassembly level = 2. It is a basic diagram which shows roughly the flow of the wavelet transformation and wavelet inverse transformation by this invention. It is a flowchart for demonstrating the example of the flow of an encoding process. It is a block diagram which shows the structure of an example of the image decoding apparatus to which this invention is applied. It is a flowchart for demonstrating the example of the flow of a decoding process. It is a basic diagram which shows roughly the parallel operation of an example of each element of the image coding apparatus and image decoding apparatus to which this invention is applied. It is a block diagram which shows the structure of an example of the image coding apparatus to which this invention is applied. It is a basic diagram for demonstrating the flow of a process when the rearrangement process of a wavelet coefficient is performed by the image coding apparatus side. It is a basic diagram for demonstrating the flow of a process when the rearrangement process of a wavelet coefficient is performed by the image decoding apparatus side. It is a block diagram which shows the structure of an example of the image coding apparatus to which this invention is applied. It is a block diagram which shows the structure of an example of the image decoding apparatus to which this invention is applied. It is a schematic diagram explaining the example of the mode of transmission / reception of encoded data. It is a figure which shows the structural example of a packet. It is a block diagram which shows the structural example of the image coding apparatus to which this invention is applied. It is a figure for demonstrating a subband. It is a figure which shows an example of the quantization coefficient encoded. It is a block diagram which shows the structural example of an entropy encoding part. It is a flowchart for demonstrating an encoding process. It is a flowchart for demonstrating an entropy encoding process. It is a flowchart for demonstrating w piece encoding process. It is a block diagram which shows the structural example of an image decoding apparatus. It is a block diagram which shows the structural example of an entropy decoding part. It is a block diagram which shows the structural example of a code division part. It is a block diagram which shows the other structural example of a code division part. It is a flowchart for demonstrating a decoding process. It is a flowchart for demonstrating an entropy decoding process. It is a flowchart for demonstrating w piece decoding process. It is a block diagram which shows the other structural example of an entropy encoding part. It is a figure which shows an example of the quantization coefficient encoded. It is a flowchart for demonstrating w piece encoding process. It is a flowchart for demonstrating w piece decoding process. It is a block diagram which shows the structure of an example of the digital triax system to which this invention is applied. It is a block diagram which shows the structure of an example of the wireless transmission system to which this invention is applied. It is a figure which shows the structure of an example of the home game device to which this invention is applied. It is a figure which shows the structural example of the information processing system to which this invention is applied.

Explanation of symbols

  1 image encoding device, 10 wavelet transform unit, 11 intermediate calculation buffer unit, 12 coefficient rearranging buffer unit, 13 coefficient rearranging unit, 14 rate control unit, 15 entropy encoding unit, 20 image decoding device, 21 entropy Decoding unit, 22 coefficient buffer unit, 23 wavelet inverse transform unit, 30 image coding device, 31 code rearrangement buffer unit, 32 code rearrangement unit, 41 image coding device, 42 image decoding device, 43 for coefficient rearrangement Buffer unit, 111 Image encoding device, 121 Wavelet transform unit, 122 Quantization unit, 123 Entropy encoding unit, 161 Line determination unit, 162 VLC encoding unit, 163 Maximum significant digit calculation unit, 164 VLC encoding unit, 165 significant digit extraction unit, 166 VLC encoding unit, 167 sign extraction unit, 168 VLC encoding unit, 169 code concatenation unit, 211 image decoding device, 221 LOPI decoding unit, 222 inverse quantization unit, 223 wavelet inverse transformation unit, 251 code division unit, 252 line decision unit, 253 generation unit, 254 VLC decoding unit, 255 VLC decoding unit, 256 VLC decoding unit, 257 quantization coefficient synthesis Unit, 258 switching unit, 271 control unit, 272 memory, 291 control unit, 401 buffer, 500 transmission unit, 501 triax cable, 502 camera control unit, 510 video signal encoding unit, 511 video signal decoding unit, 526 video signal Decoding unit, 527 Video signal encoding unit, 600 transmission unit, 601 receiving device, 602 video signal encoding unit, 612 wireless module unit, 621 wireless module unit, 624 video signal decoding unit, 700 video camera device, 701 game for home use The body of the device

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of an example of an image encoding device applicable to the first embodiment of the present invention. The image encoding device 1 includes a wavelet transform unit 10, a midway calculation buffer unit 11, a coefficient rearranging buffer unit 12, a coefficient rearranging unit 13, a rate control unit 14, and an entropy encoding unit 15.

  The input image data is temporarily stored in the midway calculation buffer unit 11. The wavelet transform unit 10 performs wavelet transform on the image data stored in the midway calculation buffer unit 11. That is, the wavelet transform unit 10 reads out the image data from the midway calculation buffer unit 11 and performs filter processing using an analysis filter to generate low-frequency component and high-frequency component coefficient data. Store in the calculation buffer unit 11. The wavelet transform unit 10 has a horizontal analysis filter and a vertical analysis filter, and performs an analysis filter process on the image data group in both the screen horizontal direction and the screen vertical direction. The wavelet transform unit 10 reads the low-frequency component coefficient data stored in the midway calculation buffer unit 11 again, performs a filtering process using an analysis filter on the read coefficient data, and performs high-frequency component and low-frequency component data processing. Further generate coefficient data. The generated coefficient data is stored in the midway calculation buffer unit 11.

  When the decomposition level reaches a predetermined level by repeating this process, the wavelet transform unit 10 reads coefficient data from the midway calculation buffer unit 11 and writes the read coefficient data to the coefficient rearranging buffer unit 12.

  The coefficient rearranging unit 13 reads out the coefficient data written in the coefficient rearranging buffer unit 12 in a predetermined order and supplies it to the entropy encoding unit 15. The entropy encoding unit 15 encodes the supplied coefficient data using a predetermined entropy encoding method such as Huffman encoding or arithmetic encoding.

  The entropy encoding unit 15 operates in conjunction with the rate control unit 14 and is controlled so that the bit rate of the output compressed encoded data becomes a substantially constant value. That is, the rate control unit 14 is based on the encoded data information from the entropy encoding unit 15 and immediately before the bit rate of the data compressed and encoded by the entropy encoding unit 15 reaches the target value or immediately before reaching the target value. Then, a control signal for controlling to end the encoding process by the entropy encoding unit 15 is supplied to the entropy encoding unit 15. The entropy encoding unit 15 outputs the encoded data when the encoding process is completed according to the control signal supplied from the rate control unit.

  The process performed by the wavelet transform unit 10 will be described in more detail. First, the wavelet transform will be schematically described. In the wavelet transform for image data, as schematically shown in Fig. 2, the process of dividing the image data into a high spatial frequency band and a low spatial frequency is performed on low spatial frequency data obtained as a result of the division. And repeat recursively. In this way, efficient compression coding can be performed by driving data of a low spatial frequency band into a smaller area.

  FIG. 2 shows an example in which the division processing into the low-frequency component region L and the high-frequency component region H with respect to the lowest-frequency component region of the image data is repeated three times, and the division level = 3. In FIG. 2, “L” and “H” represent the low-frequency component and the high-frequency component, respectively, and the order of “L” and “H” indicates the band obtained by dividing the front side in the horizontal direction, and the rear side is The band resulting from division in the vertical direction is shown. The numbers before "L" and "H" indicate the division level of the area.

  Further, as can be seen from the example in FIG. 2, processing is performed in stages from the lower right area to the upper left area of the screen, and the low frequency components are driven. That is, in the example of FIG. 2, the lower right region of the screen is the region 3HH with the lowest low frequency component (the highest frequency component is included). The upper left region is further divided into four parts. The region at the upper left corner is the region 0LL including the most low frequency components.

  The reason why the low-frequency component is repeatedly converted and divided is that the energy of the image is concentrated on the low-frequency component. This is because, as the division level is advanced from the division level = 1 example shown in FIG. 3A to the division level = 3 example shown in FIG. It is understood from the fact that subbands are formed as shown in B. For example, the division level of the wavelet transform in FIG. 2 is 3, and as a result, 10 subbands are formed.

  The wavelet transform unit 10 normally performs the above-described processing using a filter bank composed of a low-pass filter and a high-pass filter. Since a digital filter usually has an impulse response having a plurality of taps, that is, a filter coefficient, it is necessary to buffer in advance input image data or coefficient data that can be filtered. Similarly, when wavelet transform is performed in multiple stages, it is necessary to buffer the wavelet transform coefficients generated in the previous stage as many times as can be filtered.

  Next, as a specific example of the wavelet transform applicable to the first embodiment of the present invention, a method using a 5 × 3 filter will be described. This method using a 5 × 3 filter is also adopted in the JPEG2000 standard already described in the prior art, and is an excellent method in that wavelet transform can be performed with a small number of filter taps.

The impulse response (Z conversion expression) of the 5 × 3 filter is obtained from the low-pass filter H ₀ (z) and the high-pass filter H ₁ (z) as shown in the following equations (1) and (2). Composed. From Equation (1) and Equation (2), it can be seen that the low-pass filter H ₀ (z) is 5 taps and the high-pass filter H ₁ (z) is 3 taps.

H ₀ (z) = ( ^-1 + 2z ^-1 + 6z ^-2 + 2z ^-3 -z ^-4 ) / 8 (1)
H ₁ (z) = ( ^-1 + 2z ^-1 -z ^-2 ) / 2 (2)

  According to these equations (1) and (2), the coefficients of the low frequency component and the high frequency component can be directly calculated. Here, the calculation of filter processing can be reduced by using a lifting technique. The processing on the analysis filter side that performs wavelet transform when the lifting technique is applied to the 5 × 3 filter will be schematically described with reference to FIG.

  In FIG. 4, an uppermost part, a middle part, and a lowermost part indicate a pixel column, a high frequency component output, and a low frequency component output of the input image, respectively. The uppermost row is not limited to the pixel column of the input image, but may be a coefficient obtained by the previous filter processing. Here, it is assumed that the uppermost part is an input image and a pixel row, the square mark (■) is an even-numbered pixel or line (the first is 0th), and the circle mark (●) is an odd-numbered pixel or line And

First, as a first stage, a high-frequency component coefficient d _i ¹ is generated from the input pixel string by the following equation (3).
d _i ¹ = d _i ⁰ -1/2 (s _i ⁰ + s _{i + 1} ⁰ ) (3)

Next, as a second stage, a low-frequency component coefficient s _i ¹ is generated by the following equation (4) using the generated high-frequency component coefficient and odd-numbered pixels of the input image.
s _i ¹ = s _i ⁰ +1/4 (d _i-1 ¹ + d _i ¹ ) (4)

  On the analysis filter side, the pixel data of the input image is thus decomposed into a low-frequency component and a high-frequency component by filtering processing.

  The processing on the synthesis filter side that performs wavelet inverse transformation for restoring the coefficients generated by wavelet transformation will be schematically described with reference to FIG. FIG. 5 corresponds to FIG. 4 described above and shows an example in which a lifting technique is applied using a 5 × 3 filter. In FIG. 5, the uppermost part shows input coefficients generated by wavelet transform, circles (●) indicate high-frequency component coefficients, and square marks (■) indicate low-frequency component coefficients.

First, as a first step, according to the following equation (5), the coefficients of lowband components and highband components inputted, coefficient s _i ⁰ even-numbered (first to the 0-th) is generated.
s _i ⁰ = s _i ¹ −1/4 (d _i−1 ¹ + d _i ¹ ) (5)

Next, as the second stage, according to the following equation (6), the odd-numbered coefficient s _i ⁰ generated in the first stage and the input high-frequency component coefficient d _i ¹ are used. d _i ⁰ is generated.
d _i ⁰ = d _i ¹ +1/2 (s _i ⁰ + s _{i + 1} ⁰ ) (6)

  On the synthesizing filter side, the coefficients of the low frequency component and the high frequency component are synthesized by the filtering process in this way, and the wavelet inverse transformation is performed.

  Next explained is a wavelet transform method according to the first embodiment of the invention. FIG. 6 shows an example in which the filtering process using the lifting of the 5 × 3 filter described with reference to FIG. 4 is performed up to the decomposition level = 2. In FIG. 6, the part shown as the analysis filter on the left side of the figure is the filter of the wavelet transform unit 10 on the image encoding device 1 side. Also, the part shown as the synthesis filter on the right side of the figure is a filter of the wavelet inverse transform unit on the image decoding device side described later.

  In the following description, for example, in a display device, the pixel at the upper left corner of the screen is scanned from the left edge to the right edge of the screen to form one line, and scanning for each line is performed from the upper edge of the screen. It is assumed that one screen is constructed by moving toward the lower end.

  In FIG. 6, the leftmost column shows pixel data at corresponding positions on the line of the original image data arranged in the vertical direction. That is, the filter processing in the wavelet transform unit 10 is performed by vertically scanning pixels on the screen using a vertical filter. The first to third columns from the left end indicate the filter processing at the division level = 1, and the fourth to sixth columns indicate the filter processing at the division level = 2. The second column from the left end shows the high frequency component output based on the pixels of the left end original image data, and the third column from the left end shows the low frequency component output based on the original image data and the high frequency component output. The filter processing at the division level = 2 is performed on the output of the filter processing at the division level = 1 as shown in the fourth to sixth columns from the left end.

  In the filter processing at decomposition level = 1, high-frequency component coefficient data is calculated based on the pixels of the original image data as the first-stage filter processing, and calculated by the first-stage filter processing as the second-stage filter processing. The low-frequency component coefficient data is calculated based on the high-frequency component coefficient data and the pixels of the original image data. Filter processing of an example of decomposition level = 1 is shown in the first column to the third column on the left side (analysis filter side) in FIG. The calculated coefficient data of the high frequency component is stored in the coefficient rearranging buffer unit 12 described with reference to FIG. The calculated low frequency component coefficient data is stored in the midway calculation buffer unit 11.

  In FIG. 6, the coefficient rearranging buffer unit 12 is shown as a portion surrounded by a one-dot chain line, and the midway calculation buffer unit 11 is shown as a portion surrounded by a dotted line.

  Based on the result of the filter processing of decomposition level = 1 held in the midway calculation buffer unit 11, the filter processing of decomposition level = 2 is performed. In the filter processing with the decomposition level = 2, the coefficient data calculated as the low-frequency component coefficient in the filter processing with the decomposition level = 1 is regarded as the coefficient data including the low-frequency component and the high-frequency component, and the decomposition level. Performs the same filter processing as = 1. The high-frequency component coefficient data and the low-frequency component coefficient data calculated by the filter processing with the decomposition level = 2 are stored in the coefficient rearranging buffer unit 12 described with reference to FIG.

  The wavelet transform unit 10 performs the filter processing as described above in the horizontal direction and the vertical direction of the screen. For example, first, the filter processing of decomposition level = 1 is performed in the horizontal direction, and the generated high frequency component and low frequency component coefficient data is stored in the midway calculation buffer unit 11. Next, a filter process of decomposition level = 1 is performed on the coefficient data stored in the midway calculation buffer unit 11 in the vertical direction. By processing in the horizontal and vertical directions with the decomposition level = 1, the high frequency component is further divided into the high frequency component and the low frequency component. Four regions of region LH and region LL are formed by each of the coefficient data decomposed into low-frequency components.

  At the decomposition level = 2, the filter processing is performed on the low-frequency component coefficient data generated at the decomposition level = 1 for each of the horizontal direction and the vertical direction. That is, at the decomposition level = 2, the region LL formed by being divided at the decomposition level = 1 is further divided into four, and the region HH, the region HL, the region LH, and the region LL are further formed in the region LL.

  In the first embodiment, the filter processing by wavelet transform is divided into processing for several lines in the vertical direction of the screen, and is performed step by step in a plurality of times. In the example of FIG. 6, the first process that starts from the first line on the screen performs filter processing for 7 lines, and the second and subsequent processes that start from the 8th line are performed every 4 lines. Filter processing is performed. This number of lines is based on the number of lines necessary for generating the lowest frequency component for one line after dividing into two high frequency components and low frequency components.

  In the following, a line block including other subbands necessary to generate one line of this lowest frequency component (coefficient data for one line of the subband of the lowest frequency component) (Or precinct). Here, the line indicates pixel data or coefficient data for one row formed in a picture or field corresponding to image data before wavelet transform, or in each subband. That is, a line block (precinct) is a pixel data group for the number of lines necessary to generate coefficient data for one subband of the lowest band component after wavelet transformation in the original image data before wavelet transformation. Or the coefficient data group of each subband obtained by wavelet transforming the pixel data group.

According to FIG. 6, the coefficient C5 obtained by the filtering processing result of the decomposition level = 2 is calculated based on the stored coefficients C _a coefficient C4 and the intermediate calculation buffer unit 11, coefficient C4 is midway calculation buffer Calculation is performed based on the coefficient C _a , the coefficient C _b, and the coefficient C _c stored in the unit 11. Further, the coefficient _Cc is calculated based on the coefficients C2 and C3 stored in the coefficient rearranging buffer unit 12, and the pixel data of the fifth line. The coefficient C3 is calculated based on the pixel data of the fifth line to the seventh line. Thus, in order to obtain the low-frequency component coefficient C5 at the division level = 2, the pixel data of the first line to the seventh line are required.

  On the other hand, in the second and subsequent filter processing, the coefficient data already calculated in the previous filter processing and stored in the coefficient rearranging buffer unit 12 can be used, so the number of lines required is small. I'll do it.

That is, according to FIG. 6, the coefficient C9, which is the coefficient next to the coefficient C5 among the coefficients of the low-frequency component obtained from the filter processing result of the decomposition level = 2, is the coefficient C4, the coefficient C8, and the intermediate calculation Calculated based on the coefficient C _c stored in the buffer unit 11. The coefficient C4 is already calculated by the first filtering process described above, and is stored in the coefficient rearranging buffer unit 12. Similarly, the coefficient C _c has already been calculated by the first filtering process described above, and is stored in the midway calculation buffer unit 11. Therefore, in the second filtering process, only the filtering process for calculating the coefficient C8 is newly performed. This new filtering process is performed by further using the eighth to eleventh lines.

  As described above, since the second and subsequent filtering processes can use the data calculated by the previous filtering process and stored in the midway calculation buffer unit 11 and the coefficient rearranging buffer unit 12, each four lines are used. This is all you need to do.

  If the number of lines on the screen does not match the number of encoded lines, the original image data lines are copied in a predetermined manner, and the number of lines is matched with the number of encoded lines, and filtering is performed.

  Although details will be described later, in the present invention, the filtering process sufficient to obtain coefficient data for one line of the lowest frequency component is divided into a plurality of times for each line of the entire screen (line block). By doing so, it is possible to obtain a decoded image with low delay when encoded data is transmitted.

  In order to perform wavelet transform, there are a first buffer used for executing the wavelet transform itself and a second buffer for storing coefficients generated while executing processing up to a predetermined division level. Needed. The first buffer corresponds to the midway calculation buffer unit 11, and is shown surrounded by a dotted line in FIG. Further, the second buffer corresponds to the coefficient rearranging buffer unit 12, and is shown surrounded by an alternate long and short dash line in FIG. Since the coefficients stored in the second buffer are used in decoding, they are subjected to entropy encoding processing at the subsequent stage.

  The processing of the coefficient rearranging unit 13 will be described. As described above, the coefficient data calculated by the wavelet transform unit 10 is stored in the coefficient rearranging buffer unit 12, read out by the coefficient rearranging unit 13 and rearranged by the coefficient rearranging unit 13, and then sent to the entropy encoding unit 15. Sent out.

  As already described, in the wavelet transform, coefficients are generated from the high frequency component side to the low frequency component side. In the example of FIG. 6, at the first time, the high-frequency component coefficient C1, coefficient C2, and coefficient C3 are sequentially generated from the pixel data of the original image by the filter processing of decomposition level = 1. Then, the filter processing of decomposition level = 2 is performed on the coefficient data of the low frequency component obtained by the filter processing of decomposition level = 1, and the low frequency component coefficient C4 and the coefficient C5 are sequentially generated. That is, in the first time, coefficient data is generated in the order of coefficient C1, coefficient C2, coefficient C3, coefficient C4, and coefficient C5. The generation order of the coefficient data is always in this order (order from high to low) on the principle of wavelet transform.

  On the other hand, on the decoding side, it is necessary to generate and output an image from a low frequency component in order to perform immediate decoding with low delay. For this reason, it is desirable that the coefficient data generated on the encoding side is rearranged from the lowest frequency component side to the higher frequency component side and supplied to the decoding side.

  This will be described more specifically with reference to the example of FIG. The right side of FIG. 6 shows the synthesis filter side that performs inverse wavelet transform. The first synthesis process (inverse wavelet transform process) including the first line of the output image data on the decoding side is performed with the coefficients C4 and C5 of the lowest frequency component generated by the first filtering process on the encoding side. , Using the coefficient C1.

That is, in the first synthesis process, coefficient data is supplied from the encoding side to the decoding side in the order of coefficient C5, coefficient C4, and coefficient C1, and on the decoding side, the synthesis level is a synthesis process corresponding to decomposition level = 2. = 2 processing, performs composition processing to generate a coefficient C _f the coefficient C5 and the coefficient C4, and stores it in the buffer. Then, with the division level = 1 processing of the synthesis level = 1 which is synthesizing processing corresponding, it performs combining processing to the coefficient C _f and the coefficient C1, and outputs the first line.

  Thus, in the first synthesis process, the coefficient data generated on the encoding side in the order of coefficient C1, coefficient C2, coefficient C3, coefficient C4, coefficient C5 and stored in the coefficient rearranging buffer unit 12 is The coefficients C5, C4, C1,... Are rearranged in this order and supplied to the decoding side.

  On the synthesis filter side shown on the right side of FIG. 6, for the coefficients supplied from the encoding side, the coefficient numbers on the encoding side are written in parentheses, and the line order of the synthesis filter is written outside the parentheses. For example, the coefficient C1 (5) indicates that it is the coefficient C5 on the analysis filter side on the left side of FIG. 6 and the first line on the synthesis filter side.

  The decoding-side combining process using the coefficient data generated in the second and subsequent filtering processes on the encoding side can be performed using the coefficient data supplied from the combining or encoding side in the previous combining process. In the example of FIG. 6, the second combining process on the decoding side, which is performed using the low-frequency component coefficients C8 and C9 generated by the second filtering process on the encoding side, is performed on the first side on the encoding side. The coefficients C2 and C3 generated by the filter processing are further required, and the second to fifth lines are decoded.

That is, in the second combining process, coefficient data is supplied from the encoding side to the decoding side in the order of coefficient C9, coefficient C8, coefficient C2, and coefficient C3. Storing the decoding side, in the processing of synthetic level = 2, the coefficient C8 and coefficient C9, produces a coefficient C _g by using the first coefficient supplied from the encoding side in the synthesis process of C4, the buffer To do. And the coefficient C _g, and the coefficient C4 described above, generates the coefficient C _h using the coefficient C _f stored in the generated buffer by the first combining process and stored in a buffer.

Then, in the process of synthesis level = 1, the coefficient C _g and coefficient C _h stored in the buffer generated in the process of synthesizing level = 2, the coefficient C2 (synthesis filter supplied from the encoding side coefficient C6 (2 ) And the coefficient C3 (denoted as coefficient C7 (3) in the synthesis filter), the synthesis process is performed, and the second to fifth lines are decoded.

  Thus, in the second synthesis process, coefficient data generated in the order of coefficient C2, coefficient C3, (coefficient C4, coefficient C5), coefficient C6, coefficient C7, coefficient C8, and coefficient C9 on the encoding side , Coefficient C9, coefficient C8, coefficient C2, coefficient C3,... Are rearranged in this order and supplied to the decoding side.

  Similarly, in the third and subsequent synthesis processes, the coefficient data stored in the rearrangement buffer unit 12 is rearranged in a predetermined manner and supplied to the decoding unit, and the lines are decoded every four lines.

  Note that in the decoding side compositing process corresponding to the filtering process including the bottom line of the screen on the encoding side (hereinafter referred to as the last round), all the coefficient data generated in the previous process and stored in the buffer are all processed. Since it will output, the number of output lines will increase. In the example of FIG. 6, 8 lines are output in the last round.

  Note that the coefficient data rearrangement process by the coefficient rearrangement unit 13 is performed, for example, by setting a read address when reading coefficient data stored in the coefficient rearrangement buffer unit 12 in a predetermined order.

  The processing up to the above will be described more specifically with reference to FIG. FIG. 7 shows an example in which the filter processing by wavelet transform is performed up to the decomposition level = 2 using a 5 × 3 filter. In the wavelet transform unit 10, as shown in FIG. 7A, the first filtering process is performed on the first line to the seventh line of the input image data in the horizontal and vertical directions, respectively (in FIG. 7). A In-1).

  In the process of decomposition level = 1 in the first filtering process, coefficient data for three lines of coefficient C1, coefficient C2, and coefficient C3 is generated, and decomposition level = 1 as shown in FIG. 7B. Are arranged in each of the region HH, the region HL, and the region LH formed by (WT-1 in FIG. 7B).

  Further, the region LL formed with the decomposition level = 1 is further divided into four by the horizontal and vertical filter processing with the decomposition level = 2. The coefficient C5 and coefficient C4 generated at the decomposition level = 2 are arranged in the area LL with the decomposition level = 1, and one line with the coefficient C5 is arranged in the area LL, and the coefficient is added to each of the areas HH, HL, and LH. One line by C4 is arranged.

  In the second and subsequent filter processing by the wavelet transform unit 10, the filter processing is performed every four lines (In-2 in FIG. 7A), and coefficient data for each two lines is generated at the decomposition level = 1. (WT-2 in FIG. 7B), coefficient data is generated line by line at the decomposition level = 2.

  In the second example of FIG. 6, coefficient data for two lines of coefficient C6 and coefficient C7 is generated by the filter processing of decomposition level = 1, and is formed at decomposition level 1 as shown in FIG. 7B. The area HH, the area HL, and the area LH are arranged next to the coefficient data generated by the first filtering process. Similarly, in the region LL with the decomposition level = 1, the coefficient C9 for one line generated by the filter processing with the decomposition level = 2 is arranged in the region LL, and the coefficient C8 for one line is the region HH, the region HL, and Arranged in each region LH.

  When the wavelet transformed data is decoded as shown in FIG. 7B, as shown in FIG. 7C, the first filtering process by the first to seventh lines on the encoding side is performed. Thus, the first line resulting from the first combining process on the decoding side is output (Out-1 in FIG. 7C). Thereafter, for the filtering process from the second time on the encoding side to the time before the last time, four lines are output on the decoding side (Out-2 in FIG. 7C). Then, 8 lines are output on the decoding side with respect to the last filtering process on the encoding side.

  The coefficient data generated by the wavelet transform unit 10 from the high frequency component side to the low frequency component side is sequentially stored in the coefficient rearranging buffer unit 12. When the coefficient data is accumulated in the coefficient rearranging buffer unit 12 until the above-described coefficient data can be rearranged, the coefficient rearranging unit 13 sorts the coefficients from the coefficient rearranging buffer unit 12 in the order necessary for the synthesis process. Read the coefficient data instead. The read coefficient data is sequentially supplied to the entropy encoding unit 15.

  The entropy encoding unit 15 controls the encoding operation for the supplied coefficient data based on the control signal supplied from the rate control unit 14 so that the bit rate of the output data becomes the target bit rate, and the entropy encoding unit 15 Encode. Entropy-encoded encoded data is supplied to the decoding side. As encoding methods, known techniques such as Huffman encoding and arithmetic encoding are conceivable. Of course, the present invention is not limited to these, and other encoding methods may be used as long as reversible encoding processing is possible.

  Note that the entropy encoding unit 15 first quantizes the coefficient data read from the coefficient rearranging unit 13, and performs Huffman encoding, arithmetic encoding, etc. on the obtained quantized coefficient. If the information source encoding process is performed, further improvement of the compression effect can be expected. Any quantization method may be used. For example, general means, that is, coefficient data W as shown in the following equation (7) is divided by a quantization step size Δ. A technique may be used.

  Quantization coefficient = W / Δ (7)

  As described with reference to FIGS. 6 and 7, in the first embodiment of the present invention, the wavelet transform unit 10 performs wavelet transform processing for each of a plurality of lines (each line block) of image data. The encoded data encoded by the entropy encoding unit 15 is output for each line block. In other words, when the above 5 × 3 filter is used and processing is performed up to the resolution level = 2, in the output of data for one screen, the first is one line, and the second to the last round is 4 lines. Each time, the last round gives 8 lines of output.

  Note that when entropy encoding is performed on the coefficient data after being rearranged by the coefficient rearranging unit 13, for example, in the first filtering process illustrated in FIG. 6, when entropy encoding is performed on the first line of the coefficient C5. There is no past line, that is, a line for which coefficient data has already been generated. Therefore, in this case, only this one line is entropy encoded. In contrast, when the coefficient C1 line is encoded, the coefficient C5 and coefficient C4 lines are past lines. Since it is conceivable that these adjacent lines are composed of similar data, it is effective to entropy code these lines together.

  In the above description, the wavelet transform unit 10 performs the filter processing by wavelet transform using the 5 × 3 filter, but this is not limited to this example. For example, the wavelet transform unit 10 can use a filter having a longer tap number, such as a 9 × 7 filter. In this case, if the number of taps of the filter is long, the number of lines stored in the filter also increases, so that the delay time from the input of image data to the output of encoded data becomes long.

  In the above description, the wavelet transform decomposition level is set to decomposition level = 2 for the sake of explanation. However, this is not limited to this example, and the decomposition level can be further increased. The higher the decomposition level, the higher the compression ratio can be realized. For example, in general, in wavelet transform, filter processing is repeated up to decomposition level = 4. Note that if the decomposition level increases, the delay time also increases.

  Therefore, when applying the first embodiment of the present invention to an actual system, the number of filter taps and the decomposition level are determined according to the delay time required for the system and the image quality of the decoded image. It is preferable. The number of taps and the decomposition level of this filter can be adaptively selected without being fixed values.

  Next, an example of a specific flow of the entire encoding process performed by the image encoding device 1 as described above will be described with reference to the flowchart of FIG.

  When the encoding process is started, the wavelet transform unit 10 initializes the number A of the processing target line block in step S1. In the normal case, the number A is set to “1”. When the setting is completed, in step S2, the wavelet transform unit 10 obtains image data of the number of lines (that is, one line block) necessary to generate the A-th one line from the top in the lowest frequency subband, In step S3, vertical analysis filtering processing is performed on the image data arranged in the vertical direction on the screen, and analysis filtering processing is performed on image data arranged in the horizontal direction on the screen in step S4. Perform analysis filtering processing.

  In step S5, the wavelet transform unit 10 determines whether or not the analysis filtering process has been performed up to the final level, and if it is determined that the decomposition level has not reached the final level, the process returns to step S3 to return to the current decomposition level. On the other hand, the analysis filtering process of step S3 and step S4 is repeated.

  If it is determined in step S5 that the analysis filtering process has been performed to the final level, the wavelet transform unit 10 advances the process to step S6.

  In step S6, the coefficient rearranging unit 13 rearranges the coefficients of the line block A (the A-th line block from the top of the picture (field in the case of the interlace method)) in the order from low to high. In step S7, the entropy encoding unit 15 performs entropy encoding on the coefficient for each line. When the entropy encoding is completed, the entropy encoding unit 15 sends the encoded data of the line block A to the outside in step S8.

  The wavelet transform unit 10 increments the value of the number A by “1” in step S9 and sets the next line block as a processing target. It is determined whether or not an image input line exists. If it is determined that the image input line exists, the process returns to step S2, and the subsequent processing is repeated for the new processing target line block.

  As described above, the processing from step S2 to step S10 is repeatedly executed, and each line block is encoded. If it is determined in step S10 that there is no unprocessed image input line, the wavelet transform unit 10 ends the encoding process for the picture. The encoding process is newly started for the next picture.

  In the case of the conventional wavelet transform method, first, horizontal analysis filtering processing is performed on the entire picture (field in the case of the interlace method), and then vertical analysis filtering processing is performed on the entire picture. Then, the same horizontal analysis filtering process and vertical analysis filtering process are sequentially performed on the entire obtained low-frequency component. As described above, the analysis filtering process is recursively repeated until the decomposition level reaches the final level. Therefore, it is necessary to hold the result of each analysis filtering process in the buffer. At this time, the buffer stores the filtering result of the entire picture (field in the case of the interlace method) or the entire low-frequency component of the decomposition level at that time. Must be held, and a large memory capacity is required (a large amount of data is held).

  In this case, if all wavelet transforms are not completed within a picture (field in the case of an interlace method), rearrangement of coefficients and entropy coding cannot be performed, and the delay time increases.

  In contrast, in the case of the wavelet transform unit 10 of the image encoding device 1, as described above, the vertical analysis filtering process and the horizontal analysis filtering process are continuously performed up to the final level in units of line blocks. Thus, the amount of data that needs to be held (buffered) at the same time (simultaneously) is small, and the amount of buffer memory to be prepared can be greatly reduced. Further, by performing the analysis filtering process up to the final level, it is possible to perform subsequent processes such as coefficient rearrangement and entropy encoding (that is, coefficient rearrangement and entropy encoding can be performed in units of line blocks). ). Therefore, the delay time can be greatly reduced as compared with the conventional method.

  FIG. 9 shows a configuration of an example of an image decoding device corresponding to the image encoding device 1 of FIG. The encoded data (encoded data output in FIG. 1) output from the entropy encoding unit 15 of the image encoding device 1 in FIG. 1 is supplied to the entropy decoding unit 21 in the image decoding device 20 in FIG. 9 (FIG. 9). Entropy code is decoded into coefficient data. The coefficient data is stored in the coefficient buffer unit 22. The wavelet inverse transform unit 23 uses the coefficient data stored in the coefficient buffer unit 22 to perform synthesis filter processing using a synthesis filter, for example, as described with reference to FIGS. 5 and 6, and outputs the result of the synthesis filter processing. The data is stored in the coefficient buffer unit 22 again. The wavelet inverse transform unit 23 repeats this processing according to the decomposition level to obtain decoded image data (output image data).

  Next, an example of a specific flow of the entire decoding process by the image decoding device 20 as described above will be described with reference to the flowchart of FIG.

  When the decoding process is started, the entropy decoding unit 21 acquires encoded data in step S31, and entropy decodes the encoded data for each line in step S32. In step S33, the coefficient buffer unit 22 holds the coefficient obtained by decoding. In step S34, the wavelet inverse transform unit 23 determines whether or not the coefficients for one line block are accumulated in the coefficient buffer unit 22, and if it is determined that the coefficients are not accumulated, the process returns to step S31, and the subsequent steps The process is executed, and the process waits until a coefficient for one line block is accumulated in the coefficient buffer unit 22.

  When it is determined in step S34 that the coefficients for one line block have been accumulated in the coefficient buffer unit 22, the wavelet inverse transform unit 23 proceeds to step S35, and the coefficients held in the coefficient buffer unit 22 are converted into one line block. Read minutes.

  In step S36, the wavelet inverse transform unit 23 performs vertical synthesis filtering processing on the coefficients arranged in the screen vertical direction, and performs vertical synthesis filtering processing in step S37. Horizontal synthesis filtering processing is performed on the coefficients, and whether or not synthesis filtering processing has been completed up to level 1 (the level of decomposition level is “1”) in step S38, that is, before wavelet transform It is determined whether or not the reverse conversion has been performed up to the state, and if it is determined that the level has not been reached, the process returns to step S36, and the filtering processes in steps S36 and S37 are repeated.

  If it is determined in step S38 that the inverse transform process has been completed up to level 1, the wavelet inverse transform unit 23 proceeds to the process in step S39, and outputs the image data obtained by the inverse transform process to the outside.

  In step S40, the entropy decoding unit 21 determines whether or not to end the decoding process, and when it is determined that the input of encoded data continues and does not end the decoding process, the process returns to step S31, The subsequent processing is repeated. Also, in step S40, when it is determined that the decoding process is to be ended because input of encoded data is ended, the entropy decoding unit 21 ends the decoding process.

  In the case of the conventional wavelet inverse transformation method, the horizontal synthesis filtering process is first performed in the horizontal direction on the screen and then the vertical synthesis filtering process is performed in the vertical direction on the screen with respect to all coefficients of the decomposition level to be processed. In other words, for each synthesis filtering process, the result of the synthesis filtering process needs to be held in the buffer. At this time, the buffer stores the synthesis filtering result of the current decomposition level and all coefficients of the next decomposition level. Must be held, and a large memory capacity is required (a large amount of data is held).

  Further, in this case, since image data output is not performed until all wavelet inverse transforms are completed in the picture (field in the case of the interlace method), the delay time from input to output increases.

  On the other hand, in the case of the wavelet inverse transform unit 23 of the image decoding device 20, the vertical synthesis filtering process and the horizontal synthesis filtering process are continuously performed up to level 1 in units of line blocks as described above, which is compared with the conventional method. Thus, the amount of data that needs to be buffered at the same time (simultaneously) is small, and the amount of buffer memory to be prepared can be greatly reduced. In addition, by performing synthesis filtering processing (inverse wavelet transform processing) up to level 1, image data can be sequentially output (in line block units) before all image data in a picture is obtained. The delay time can be greatly reduced as compared with.

  The operation of each element of the image encoding device 1 shown in FIG. 1 and the image decoding device 20 shown in FIG. 9 (the encoding process in FIG. 8 and the decoding process in FIG. 10) is, for example, a CPU (Central Processing Unit) is controlled according to a predetermined program. The program is stored in advance in a ROM (Read Only Memory) (not shown), for example. However, the present invention is not limited to this, and it is also possible to exchange timing signals and control signals between the elements constituting the image encoding device and the image decoding device so as to operate as a whole. Further, the image encoding device and the image decoding device can be realized by software operating on a computer device.

  Next, a second embodiment of the present invention will be described. In the second embodiment, in the system described in the first embodiment, the elements of the image encoding device 1 and the image decoding device 20 are operated in parallel to compress and encode and decode an image. The processing is performed with lower delay.

  In the second embodiment, the image encoding device 1 and the image decoding device 20, and the encoding method and decoding method described with reference to FIGS. 1 to 10 in the first embodiment are unchanged. These descriptions are omitted to avoid complexity as they are applicable.

  FIG. 11 schematically shows a parallel operation of an example of each element of the image encoding device 1 and the image decoding device 20 according to the second embodiment of the present invention. FIG. 11 corresponds to FIG. 7 described above. The entropy encoding unit 15 performs the first wavelet transform WT-1 on the input In-1 (A in FIG. 11) of the image data (B in FIG. 11). As described with reference to FIG. 6, the first wavelet transform WT-1 is started when the first three lines are input, and the coefficient C1 is generated. That is, a delay of 3 lines occurs from the input of the image data In-1 until the wavelet transform WT-1 is started.

  The generated coefficient data is stored in the coefficient rearranging buffer unit 12. Thereafter, wavelet transform is performed on the input image data, and when the first process is completed, the process proceeds to the second wavelet transform WT-2.

  In parallel with the input of the image data In-2 for the second wavelet transform WT-2 and the processing of the second wavelet transform WT-2, the coefficient rearrangement unit 13 performs three coefficients C1 and coefficient. Rearrangement Ord-1 of C4 and coefficient C5 is executed (C in FIG. 11).

  Note that the delay from the end of the wavelet transform WT-1 to the start of the reordering Ord-1 is, for example, a delay associated with the transmission of a control signal instructing the coefficient reordering unit 13 to perform the reordering process, This delay is based on the apparatus and system configuration, such as the delay required for starting the processing of the coefficient rearranging unit 13 and the delay required for the program processing, and is not an essential delay in the encoding process.

  The coefficient data is read from the coefficient rearranging buffer unit 12 in the order in which the rearrangement is completed, and is supplied to the entropy encoding unit 15, where entropy encoding EC-1 is performed (D in FIG. 11). This entropy coding EC-1 can be started without waiting for the end of the rearrangement of all three coefficients C1, C4, and C5. For example, entropy coding for the coefficient C5 can be started when the rearrangement of one line by the coefficient C5 that is output first is completed. In this case, the delay from the start of rearrangement Ord-1 processing to the start of entropy coding EC-1 processing is one line.

  The encoded data that has undergone entropy encoding EC-1 by the entropy encoding unit 15 is transmitted to the image decoding device 20 via some transmission path (E in FIG. 11). As a transmission path through which encoded data is transmitted, for example, a communication network such as the Internet can be considered. In this case, the encoded data is transmitted by IP (Internet Protocol). The transmission path of the encoded data is not limited to this, and communication interfaces such as USB (Universal Serial Bus) and IEEE1394 (Institute Electrical and Electronics Engineers 1394), and wireless communication represented by the IEEE802.11 standard are also conceivable.

  Image data is sequentially input to the image encoding device 1 up to the lowermost line on the screen, following the input of image data for seven lines in the first process. In the image encoding device 1, with the input In-n (n is 2 or more) of image data, as described above, the wavelet transform WT-n, the rearrangement Ord-n, and the entropy encoding EC- Do n. The rearrangement Ord and the entropy encoding EC for the last processing in the image encoding device 1 are performed for six lines. These processes are performed in parallel in the image encoding device 1 as illustrated in A of FIG. 11 to D of FIG.

  The encoded data encoded by the entropy encoding EC-1 by the image encoding device 1 is transmitted to the image decoding device 20 via the transmission path and supplied to the entropy decoding unit 21. The entropy decoding unit 21 sequentially performs entropy decoding iEC-1 on the supplied encoded data encoded by the entropy encoding EC-1 to restore coefficient data (F in FIG. 11). ). The restored coefficient data is sequentially stored in the coefficient buffer unit 22. The wavelet inverse transform unit 23 reads the coefficient data from the coefficient buffer unit 22 after the coefficient data is stored in the coefficient buffer unit 22 so that the wavelet inverse transform can be performed, and uses the read coefficient data to perform the wavelet inverse transform iWT- 1 is performed (G in FIG. 11).

  As described with reference to FIG. 6, the wavelet inverse transformation iWT-1 by the wavelet inverse transformation unit 23 can be started when the coefficient C4 and the coefficient C5 are stored in the coefficient buffer unit 22. Therefore, the delay from the start of decoding iEC-1 by the entropy decoding unit 21 to the start of wavelet inverse transformation iWT-1 by the wavelet inverse transformation unit 23 is two lines.

  When the wavelet inverse transformation unit 23 completes the wavelet inverse transformation iWT-1 for three lines by the first wavelet transformation, the output Out-1 of the image data generated by the wavelet inverse transformation iWT-1 is performed (FIG. 11). H). In the output Out-1, the image data of the first line is output as described with reference to FIGS.

  Encoded by entropy encoding EC-n (n is 2 or more) following the input of the encoded coefficient data for three lines by the first processing in the image encoding device 1 to the image decoding device 20 The coefficient data is sequentially input. The image decoding device 20 performs entropy decoding iEC-n and wavelet inverse transformation iWT-n for every four lines on the input coefficient data as described above, and is restored by the wavelet inverse transformation iWT-n. Image data output Out-n is performed sequentially. Entropy decoding iEC and inverse wavelet transform iWT corresponding to the last time of the image coding apparatus are performed on 6 lines, and 8 lines are output as output Out. These processes are performed in parallel in the image decoding apparatus as illustrated in F of FIG. 11 to H of FIG.

  As described above, image compression processing and image decoding processing are performed with lower delay by performing each processing in the image encoding device 1 and the image decoding device 20 in parallel in the order from the top to the bottom of the screen. It becomes possible.

  Referring to FIG. 11, let us calculate the delay time from image input to image output when wavelet transform is performed up to decomposition level = 2 using a 5 × 3 filter. The delay time from when the image data of the first line is input to the image encoding device 1 to when the image data of the first line is output from the image decoding device 20 is the sum of the following elements. . Here, delays that differ depending on the system configuration, such as delays in the transmission path and delays associated with actual processing timing of each unit of the apparatus, are excluded.

(1) Delay D_WT from the first line input until the end of wavelet transform WT-1 for 7 lines
(2) Time D_Ord associated with reordering Ord-1 for 3 lines
(3) Time D_EC associated with entropy coding EC-1 for 3 lines
(4) Time D_iEC associated with entropy decoding iEC-1 for 3 lines
(5) Time D_iWT associated with wavelet inverse iWT-1 for 3 lines

  Referring to FIG. 11, an attempt is made to calculate a delay by each of the above elements. The delay D_WT in (1) is a time for 10 lines. The time D_Ord in (2), the time D_EC in (3), the time D_iEC in (4), and the time D_iWT in (5) are times for three lines, respectively. In the image encoding device 1, entropy encoding EC-1 can be started one line after the rearrangement Ord-1 is started. Similarly, in the image decoding device 20, the wavelet inverse transformation iWT-1 can be started two lines after the entropy decoding iEC-1 is started. In addition, the entropy decoding iEC-1 can start processing when encoding for one line is completed in the entropy encoding EC-1.

  Therefore, in the example of FIG. 11, the delay time from when the image data of the first line is input to the image encoding apparatus to when the image data of the first line is output from the image decoding apparatus is 10 + 1 + 1 + 2 + 3 = 17 lines.

  Consider the delay time with a more specific example. When the input image data is an HDTV (High Definition Television) interlace video signal, for example, one frame is configured with a resolution of 1920 pixels × 1080 lines, and one field is 1920 pixels × 540 lines. Therefore, when the frame frequency is 30 Hz, 540 lines in one field are input to the image encoding device 1 at a time of 16.67 msec (= 1 sec / 60 fields).

  Therefore, the delay time associated with the input of the image data for 7 lines is 0.216 msec (= 16.67 msec × 7/540 lines), which is a very short time with respect to the update time of one field, for example. In addition, regarding the sum of the delay D_WT of (1), the time D_Ord of (2), the time D_EC of (3), the time D_iEC of (4), and the time D_iWT of (5), the number of lines to be processed is Since the delay time is small, the delay time is greatly reduced. If the elements for performing each process are implemented as hardware, the processing time can be further shortened.

  Next, a third embodiment of the present invention will be described. In the first and second embodiments described above, the image encoding apparatus 1 rearranges the coefficient data after performing wavelet transform. On the other hand, in the third embodiment of the present invention, the rearrangement of coefficient data is performed after entropy coding. That is, in this case, the image coding apparatus performs wavelet transform on the input image data, performs entropy coding on the generated coefficient, and performs rearrangement processing on the entropy coded data. . In this way, the storage capacity required in the coefficient rearrangement buffer can be suppressed by rearranging the coefficient data after entropy encoding.

  For example, when the bit accuracy of the input image data is 8 bits, the bit accuracy of the generated coefficient data is, for example, about 12 bits when the wavelet transform is performed up to multi-level decomposition. When the coefficient rearrangement process is performed before the entropy encoding process, the coefficient rearrangement buffer unit needs to store the coefficient data having a bit accuracy of 12 bits for a predetermined number of lines. If the coefficient data generated by the wavelet transform is subjected to entropy encoding and then rearranged, the coefficient rearrangement buffer only needs to store data compressed by entropy encoding. It will be over.

  FIG. 12 shows a configuration of an example of an image encoding device according to the third embodiment of the present invention. In FIG. 12, parts common to those in FIG. 1 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  The input image data is temporarily stored in the midway calculation buffer unit 11 of the image encoding device 30. The wavelet transform unit 10 performs predetermined wavelet transform on the image data stored in the midway calculation buffer unit 11 as already described in the first embodiment. The coefficient data generated by the wavelet transform is supplied to the entropy encoding unit 15. The entropy encoding unit 15 operates in conjunction with the rate control unit 14 and is controlled so that the bit rate of the output compression encoded data becomes a substantially constant value. Entropy encoding is performed on the supplied coefficient data. Process. That is, the entropy encoding unit 15 encodes the acquired coefficients in the same order in the acquired order regardless of the order of the coefficients.

  The encoded data obtained by entropy encoding the coefficient data generated by the wavelet transform by the entropy encoding unit 15 is temporarily stored in the code rearranging buffer unit 31. The code rearrangement unit 32 rearranges and reads the encoded data from the code rearrangement buffer unit 31 as soon as the encoded data to be rearranged is stored in the code rearrangement buffer unit 31. As already described in the first embodiment, the coefficient data generated by the wavelet transform unit 10 is generated from the upper end side to the lower end side in the order from the high frequency component to the low frequency component. In order to output image data with low delay on the decoding side, the encoded data stored in the code rearrangement buffer unit 31 is rearranged in the order of low frequency components to high frequency components of coefficient data by wavelet transform. read out.

  The encoded data read from the code rearrangement buffer unit 31 is sent to the transmission line as output encoded data, for example.

  Note that the data encoded and output by the image encoding device 30 according to the third embodiment is processed by the image decoding device 20 according to the first embodiment already described with reference to FIG. Decoding can be performed in the same manner as in the first mode. That is, for example, the encoded data input to the image decoding device 20 via the transmission path is subjected to entropy decoding by the entropy decoding unit 21, and the coefficient data is restored. The restored coefficient data is sequentially stored in the coefficient buffer unit 22. The wavelet inverse transform unit 23 performs wavelet inverse transform on the coefficient data stored in the coefficient buffer unit 22, and outputs image data.

  Next, a fourth embodiment of the present invention will be described. In the first to third embodiments described above, the rearrangement process of the coefficient data generated by the wavelet transform is performed on the image encoding device side as shown in an example in FIG. . On the other hand, in the fourth embodiment of the present invention, the rearrangement process of the coefficient data generated by the wavelet transform is performed on the image decoding device side as shown in an example in FIG. .

  In the process of rearranging the coefficient data generated by the wavelet transform, as described in the third embodiment, a relatively large capacity is required as the storage capacity of the coefficient rearrangement buffer, and the coefficient rearrangement is performed. The processing itself requires a high processing capacity. Even in this case, when the processing capability on the image coding device side is higher than a certain level, the coefficient rearrangement processing is performed on the image coding device side as described in the first to third embodiments. There is no problem with going.

  Here, consider a case where an image encoding device is mounted on a device with relatively low processing capability, such as a so-called mobile terminal such as a mobile phone terminal or a PDA (Personal Digital Assistant). For example, in recent years, a product in which an imaging function is added to a mobile phone terminal has been widely used (referred to as a mobile phone terminal with a camera function). It is conceivable that image data captured by such a mobile phone terminal with a camera function is compressed and encoded by wavelet transform and entropy encoding and transmitted via wireless or wired communication.

  Such mobile terminals, for example, have limited CPU processing capacity, and have a certain upper limit in memory capacity. Therefore, the processing load associated with the coefficient rearrangement as described above is a problem that cannot be ignored.

  Therefore, as shown in FIG. 14, by incorporating the rearrangement process on the image decoding device side, the load on the image coding device side is reduced, and the image coding device has a relatively high processing capability such as a mobile terminal. It becomes possible to mount on low devices.

  FIG. 15 shows a configuration of an example of an image encoding device applicable to the fourth embodiment. In FIG. 15, portions common to those in FIG. 1 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  The configuration of the image encoding device 41 shown in FIG. 15 is a configuration in which the coefficient rearranging unit 13 and the coefficient rearranging buffer unit 12 are removed from the configuration of the image encoding device 1 shown in FIG. It has become. That is, in the fourth embodiment, as the image encoding device 41, a conventionally used configuration in which the wavelet transform unit 10, the midway calculation buffer unit 11, the entropy encoding unit 15, and the rate control unit 14 are combined. It is possible to apply.

  The input image data is temporarily stored in the midway calculation buffer unit 11. The wavelet transform unit 10 performs wavelet transform on the image data stored in the midway calculation buffer unit 11, and sequentially supplies the generated coefficient data to the entropy encoding unit 15 in the order of generation of the coefficient data. That is, the generated coefficient data is supplied to the entropy encoding unit 15 in the order of high frequency components to low frequency components in the order of wavelet transform. The entropy encoding unit 15 performs entropy encoding on the supplied coefficient while the bit rate of the output data is controlled by the rate control unit. Entropy encoding unit 15 outputs encoded data obtained by entropy encoding coefficient data generated by wavelet transform.

  FIG. 16 shows a configuration of an example of an image decoding apparatus according to the fourth embodiment. In FIG. 16, parts common to those in FIG. 9 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  The encoded data output from the entropy encoding unit 15 of the image encoding device 41 described in FIG. 15 is supplied to the entropy decoding unit 21 of the image decoding device 42 of FIG. 16, and the entropy code is decoded into coefficient data. The The coefficient data is stored in the coefficient rearranging buffer unit 43 via the coefficient buffer unit 22. When the coefficient data is accumulated in the coefficient rearrangement buffer unit 43 until the coefficient data can be rearranged, the wavelet inverse transform unit 23 converts the coefficient data stored in the coefficient rearrangement buffer unit 43 into a low frequency range. The components are read out in the order of the high frequency components, and the wavelet inverse transform process is performed using the coefficient data in the order of reading. When a 5 × 3 filter is used, it is as shown in FIG.

  That is, when the wavelet inverse transform unit 23 is, for example, processing from the beginning of one frame, the coefficient C1, the coefficient C4, and the coefficient C5 at which the entropy code has been decoded are stored in the coefficient rearranging buffer unit 43. Then, the coefficient data is read from the coefficient rearranging buffer unit 43, and the wavelet inverse transformation process is performed. Data subjected to the wavelet inverse transform in the wavelet inverse transform unit 23 is sequentially output as output image data.

  Even in the case of the fourth embodiment, as already described with reference to FIG. 11 in the second embodiment, the processing of each element in the image coding device 41 and the coding for the transmission path Data transmission and processing of each element in the image decoding device 42 are executed in parallel.

  Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, the encoded data exchanged between the image encoding device and the image decoding device according to the first to fourth embodiments is packetized.

  FIG. 17 is a schematic diagram illustrating an example of how the encoded data is exchanged. Also in the case of the example shown in FIG. 17, as in the other embodiments described above, image data is wavelet transformed while being input for a predetermined number of lines for each line block (subband 51). When the predetermined wavelet transform decomposition level is reached, the coefficient lines from the lowest subband to the highest subband are rearranged in the reverse order of generation, that is, in the order from low to high. .

  In the subband 51 of FIG. 17, the diagonally divided, vertical and wavy lines are different line blocks (as indicated by the arrows, the white blank portion of the subband 51 is also a line block. Are processed separately). The coefficients of the line blocks after the rearrangement are entropy encoded as described above to generate encoded data.

  Here, for example, if the image encoding apparatus sends the encoded data as it is, it may be difficult (or complicated processing is required) for the image decoding apparatus to identify the boundary of each line block. Therefore, in this embodiment, the image encoding apparatus adds a header to encoded data, for example, in units of line blocks, and transmits the packet as a packet including the header and encoded data.

  That is, as shown in FIG. 17, when the encoded data (encoded data) of the first line block (Lineblock-1) is generated, the image encoding device packetizes it and transmits it as a transmission packet 61. To send. When receiving the packet (received packet 71), the image decoding apparatus decodes (decodes) the encoded data.

  Similarly, when the encoded data of the second line block (Lineblock-2) is generated, the image encoding device packetizes it and sends it as a transmission packet 62 to the image decoding device. When receiving the packet (received packet 72), the image decoding apparatus decodes (decodes) the encoded data. Further, similarly, when the encoded data of the third line block (Lineblock-3) is generated, the image encoding apparatus packetizes it and transmits it as a transmission packet 63 to the image decoding apparatus. When receiving the packet (received packet 73), the image decoding apparatus decodes (decodes) the encoded data.

  The image encoding device and the image decoding device repeat the above processing up to the Xth final line block (Lineblock-X) (transmission packet 64, reception packet 74). As described above, the decoded image 81 is generated in the image decoding apparatus.

  FIG. 18 shows a configuration example of the header. As described above, a packet is composed of a header 91 and encoded data. The header 91 includes a description of a line block number (NUM) 93 and an encoded data length (LEN) 94. Yes.

  The image decoding apparatus can easily identify the boundary of each line block by reading the information included in the header added to the received encoded data, thereby reducing the load and processing time of the decoding process. be able to.

  In addition, as shown in FIG. 18, a description of quantization step sizes (Δ1 to ΔN) 92 for each subband constituting the line block may be added. Thereby, the image decoding apparatus can perform inverse quantization for each subband, and can perform finer image quality control.

  In addition, the image encoding device and the image decoding device perform the above-described processes such as encoding, packetizing, packet transmission / reception, and decoding for each line block as described in the fourth embodiment. Alternatively, it may be executed concurrently (in a pipeline).

  By doing in this way, the delay time until an image output is obtained in the image decoding apparatus can be significantly reduced. FIG. 17 shows an operation example with interlaced video (60 fields / second) as an example. In this example, the time for one field is 1 second ÷ 60 = about 16.7 msec, but by performing each processing in parallel, an image output can be obtained with a delay time of about 5 msec. I can do it.

  Next, a sixth embodiment of the present invention will be described. In the sixth embodiment, specific examples of entropy coding in the image coding device and entropy decoding in the image decoding device in each of the above-described embodiments will be shown. In each of the above-described embodiments, any method may be used for entropy coding. However, by using the method shown in this embodiment, the image coding apparatus performs coding by easier calculation. Therefore, delay time, power consumption, amount of buffer memory, and the like can be reduced.

  As described above, in each embodiment, the coefficient data can be quantized after entropy coding, and the coding can be performed. However, the same applies to the present embodiment, and the coefficient data is quantized. The entropy encoding may be performed after performing the above, or the coefficient data may be entropy encoded without performing the quantization. However, as will be described later, since the image quality can be further improved when quantization is performed, only entropy coding when quantization is performed will be described below. In other words, the description of the entropy encoding when the quantization is not performed is omitted, but the description of the entropy encoding when the quantization is performed can be applied.

  In the following description, description of coefficient rearrangement is omitted. In each of the above-described embodiments, description will be given of entropy coding of rearranged coefficient data, rearrangement of encoded data that has undergone entropy encoding, and rearrangement of coefficient data after entropy decoding. However, this rearrangement is basically processing for performing wavelet inverse transformation processing at high speed, and is basically unrelated to entropy encoding processing (and entropy decoding processing). Even when coefficient rearrangement is performed, since the rearrangement is performed within the line block, the specific contents will be described later, but basically the entropy encoding described in the present embodiment It does not affect. In other words, the entropy encoding method of the present embodiment can be similarly applied to the case where the coefficient data whose order has been rearranged is encoded and the case where the coefficient data before the rearrangement is encoded. Therefore, in the following description, description of coefficient rearrangement is omitted for the sake of simplicity.

  In other words, the entropy coding according to the present embodiment will be described below in the case where the entropy coding unit 15 of the image coding device 41 according to the fourth embodiment shown in FIG. 15 performs quantization processing. To do. For the same reason, only the image decoding apparatus corresponding to the image encoding apparatus in that case will be described, and the image decoding apparatus in the case where the coefficient rearrangement is performed or in the case where the inverse quantization is not performed will be described. Is omitted.

  FIG. 19 is a block diagram illustrating a configuration example of an image encoding device to which the present invention has been applied.

  The image encoding device 111 includes a wavelet transform unit 121, a quantization unit 122, and an entropy encoding unit 123.

  The wavelet transform unit 121 corresponds to, for example, the wavelet transform unit 10 in FIG. 15 and performs the same processing. That is, for example, an image (data) that is a component signal that has been subjected to DC level shift as necessary is input to the wavelet transform unit 121. The wavelet transform unit 121 performs wavelet transform on the input image and decomposes it into a plurality of subbands. The wavelet transform unit 121 supplies the subband wavelet coefficients obtained by the wavelet transform to the quantization unit 122.

  The quantization unit 122 quantizes the wavelet coefficients supplied from the wavelet transform unit 121, and supplies the resulting quantized coefficients to the entropy encoding unit 123.

  The entropy encoding unit 123 performs entropy encoding on the quantized coefficient supplied from the quantization unit 122, and outputs the code obtained thereby as an encoded image (data). The image output from the entropy encoding unit 123 is, for example, subjected to rate control processing, then packetized and recorded, or supplied to another device (not shown) connected to the image encoding device 111. To do.

  That is, the quantization unit 122 and the entropy encoding unit 123 correspond to, for example, the entropy encoding unit 15 and the rate control unit 14 in FIG.

  Next, the entropy encoding performed by the entropy encoding unit 123 of FIG. 19 will be described with reference to FIGS.

  For example, as shown in FIG. 20, it is assumed that one subband is composed of six lines L1 to L6, and the position corresponding to the pixel on the line in the xy coordinate system is (x, y). To do. Here, in the drawing of each line, the x coordinate of the left end position is 0, and the y coordinate of the line L1 is 0.

  From the quantization unit 122 to the entropy encoding unit 123, the quantization coefficient at each position (x, y) of the subband expressed in the bit plane is input from the line L1 to the line L6 in the raster scan order.

  In other words, first, a quantization coefficient corresponding to the position (0, 0) at the left end of the line L1 is input to the entropy encoding unit 123. Next, the quantization coefficient corresponding to the position (1, 0) on the right of the position (0, 0) is input to the entropy encoding unit 123, and the quantization coefficient is input up to the right end position of the line L1. The quantization coefficient corresponding to the position on the right side of the position is sequentially input to the entropy encoding unit 123. When all the quantized coefficients at the position on the line L1 are input, the quantized coefficients corresponding to the positions on the line L2 from the left end position (0, 1) of the line L2 to the right end position in order. Similarly, the quantized coefficients corresponding to the positions on the lines L3 to L6 are input to the entropy encoding unit 123 from the line L3 to the line L6.

  For example, when twelve quantized coefficients are input to the entropy encoding unit 123 in order from the quantized coefficient at the left end position of the line L1 in FIG. The encoding unit 123 encodes the quantized coefficients by a predetermined number w (w = 4 in FIG. 21).

  Here, each quantized coefficient shown in the upper left of FIG. 21 is represented by the absolute value of the code divided into binary digits (bit plane representation). In the example of FIG. 21, the entropy is expressed. The encoding unit 123 includes quantization coefficients “-0101”, “+0011”, “-0110”, “+0010”, “+0011”, “+0110” for one line (line L1 in FIG. 20). , “0000”, “−0011”, “+1101”, “−0100”, “+0111”, and “−1010” are input in order.

  One quantization coefficient is represented by a sign of a quantization coefficient represented by “+” (positive) or “−” (negative) (hereinafter referred to as a sign of the quantization coefficient) and a binary number. And the absolute value of the quantized coefficient. In FIG. 21, among the bits indicating the value of each digit of the absolute value of the quantized coefficient, the uppermost bit in the figure represents the most significant bit (the most significant digit bit). Therefore, for example, the quantization coefficient “-0101” has a sign “−” and an absolute value represented by a binary number “0101”. Therefore, when the quantization coefficient is represented by a decimal number, -5 ”.

  First, the entropy encoding unit 123 determines whether or not the quantization coefficient (absolute value) of one input line is all 0, and according to the determination result, the quantum of the line to be encoded from now on A code indicating whether or not all the quantization coefficients are 0 is output. When it is determined that the quantization coefficients are all 0, the entropy encoding unit 123 outputs 0 as a code indicating whether or not the quantization coefficients of the line are all 0, and the quantum of the currently performed line The encoding of the encoding coefficient is finished. Further, when it is determined that all the quantization coefficient values are not 0 (not only the 0 quantization coefficient), the entropy encoding unit 123 indicates whether or not the line quantization coefficients are all 0. 1 is output as a sign.

  In the figure, when the twelve quantized coefficients shown in the upper left are input, the quantized coefficient of the input line is not only 0, so the entropy encoding unit 123 performs coding as shown in the upper right in the figure. Outputs 1 as

  When code 1 indicating that the quantized coefficients are not all 0 is output as a code indicating whether or not the quantized coefficients of the line are all 0, the entropy encoding unit 123 then inputs the first The four (w) quantization coefficients “-0101”, “+0011”, “-0110”, and “+0010” are encoded.

  The entropy encoding unit 123 calculates the maximum number of significant digits (the value of the variable B in FIG. 21) of the four consecutive quantization coefficients input this time and the four (w) encoded (input) previously encoded. It compares with the maximum number of significant digits of the quantization coefficient, determines whether or not the maximum number of significant digits has changed, and outputs a code indicating the maximum number of significant digits of the quantization coefficient.

  Here, the maximum number of significant digits means the number of significant digits of the quantized coefficient having the largest absolute value among the four (w) quantized coefficients to be encoded together. In other words, the maximum number of significant digits indicates in which digit the 1 that is at the top of the quantization coefficient having the largest absolute value is among the four quantization coefficients. Thus, for example, the maximum number of significant digits of the four quantized coefficients “-0101”, “+0011”, “-0110”, and “+0010” to be encoded together is the quantized coefficient “ It is set to “3”, which is the first digit at the top of -0110 ”.

  The code indicating the maximum number of significant digits of the quantization coefficient is a code indicating whether the maximum number of significant digits has changed, a code indicating whether the maximum number of significant digits has increased or decreased, and the maximum number of significant digits. If the maximum number of significant digits has not changed, the code indicating whether the maximum number of significant digits has increased or decreased, and the code indicating the amount of change in the maximum number of significant digits are Not output.

  When the maximum number of significant digits changes as a result of the comparison of the maximum number of significant digits, the entropy encoding unit 123 outputs code 1 indicating that the maximum number of significant digits has changed, and the maximum number of significant digits has not changed. In this case, a code 0 indicating that the maximum number of significant digits has not changed is output.

  When determining whether or not the maximum number of significant digits has changed, when four quantized coefficients are input for the first time, that is, when the quantized coefficients of the subband to be encoded are input for the first time (for example, , When four quantized coefficients are input in order from the left end of line L1 in FIG. 20), since the quantized coefficients of that subband were not encoded last time, the last four encoded (w) The maximum number of significant digits of the quantization coefficient is zero.

  Therefore, the entropy encoding unit 123 previously encoded the four input quantized coefficients “-0101”, “+0011”, “-0110”, and “+0010” with the maximum number of 3 significant digits. Compares the maximum number of significant digits of the quantization coefficient with 0, and outputs the code 1 because the maximum number of significant digits has changed.

  The entropy encoding unit 123 outputs a code indicating whether the maximum number of significant digits has increased or decreased following the code 1 indicating that the maximum number of significant digits has changed. Here, the entropy encoding unit 123 outputs 0 when the maximum number of significant digits increases, and outputs 1 when the maximum number of significant digits decreases.

  Since the previous maximum number of significant digits is 0 and the current maximum number of significant digits is 3, as shown in the upper right in the figure, the entropy encoding unit 123 indicates that the maximum number of significant digits has increased. Outputs 0.

  Further, when the entropy encoding unit 123 outputs a code indicating whether the maximum number of significant digits has increased or decreased, a code indicating how much the maximum number of significant digits has increased or decreased, that is, the maximum number of significant digits. A code indicating the amount of change in the number is output. Specifically, the entropy encoding unit 123 outputs (n−1) code 0s, where n is the change amount (that is, the increase amount or the decrease amount) of the maximum number of significant digits. Subsequently, code 1 is output.

  When the first four quantized coefficients in FIG. 3 are encoded, since the change amount of the maximum number of significant digits is 3 (= 3-0), the entropy encoding unit 123 uses 2 (= 3-1) as a code. ) Outputs 0's and 1's.

  Next, the entropy encoding unit 123 outputs codes for the maximum number of significant digits indicating the absolute values of the four (w) quantization coefficients to be encoded this time. That is, the entropy coding unit 123 indicates the value of each digit of the absolute value of the quantized coefficient from the maximum significant digit indicated by the maximum number of significant digits to the smallest digit in order for each quantized coefficient. Output the sign.

  Since the quantization coefficients to be encoded this time are “-0101”, “+0011”, “-0110”, and “+0010”, the entropy encoding unit 123 firstly inputs the quantization coefficient that is input first. The code for the maximum number of significant digits indicating the absolute value of “-0101” is output. Here, since the maximum number of significant digits this time is 3, the entropy encoding unit 123 determines the maximum number of significant digits (that is, the third digit) indicated by the maximum number of significant digits of the quantization coefficient “-0101”. Value "1", the value "0" in the digit one digit below the largest digit (second digit), and the value "1" in the least significant digit are output. As a result, the code “101” corresponding to the effective number of digits indicating the absolute value of the quantization coefficient “-0101” is output.

  Similarly, the entropy encoding unit 123 generates codes “011”, “110”, and “010” corresponding to the number of significant digits indicating the absolute values of the quantization coefficients “+0011”, “-0110”, and “+0010”. "In order. Therefore, “101011110010” is output as the code for the maximum number of significant digits indicating the absolute values of “-0101”, “+0011”, “-0110”, and “+0010” as the quantization coefficient. . As described above, the entropy encoding unit 123 outputs a code having a length corresponding to the maximum number of significant digits of the four quantized coefficients to be encoded as a code indicating the absolute value of the quantized coefficient.

  Finally, the entropy encoding unit 123 outputs a code indicating each sine of the quantized coefficient whose absolute value is not 0 among the four (w) quantized coefficients. Here, the entropy encoding unit 123 outputs a code 0 when the sign of the quantization coefficient is “+” (positive), and outputs a code 1 when the sign is “−” (negative).

  The quantization coefficients to be encoded this time are “-0101”, “+0011”, “-0110”, and “+0010”, and the signs of these quantization coefficients are negative, positive, negative, and positive in this order. Therefore, as shown in the upper right in the figure, the entropy encoding unit 123 outputs “1010” as a code indicating each sign of the quantized coefficient.

  When the first four input quantized coefficients are encoded, the entropy encoding unit 123 then continues to the next four consecutive quantized coefficients “+0011”, “+0110”, “0000”, And "-0011" is encoded.

  As in the case of encoding of the first (previous) input quantized coefficient, first, the entropy encoding unit 123 first determines the maximum significant digits of the four (w) quantized coefficients newly input this time. The number is compared with the maximum number of significant digits of the four previously encoded quantization coefficients.

  The maximum number of significant digits of the four (w) quantization coefficients “+0011”, “+0110”, “0000”, and “-0011” input this time is the quantization coefficient “+” having the largest absolute value. “3”, which is the first digit of 0110 ”, is the same as the maximum number of significant digits“ 3 ”of the previously encoded quantization coefficient, so the entropy encoding unit 123 determines the maximum number of significant digits. Outputs a code 0 indicating that has not changed.

  Subsequently, the entropy encoding unit 123 indicates the absolute values of the four (w) quantization coefficients “+0011”, “+0110”, “0000”, and “−0011” to be encoded this time. A code “011110000011” in which codes “011”, “110”, “000”, and “011” corresponding to the maximum number of significant digits are arranged in order is output.

  Then, when a code indicating the absolute value of the quantized coefficient is output, the entropy encoding unit 123 outputs a code indicating each sign of the quantized coefficient whose absolute value is not 0 among the four quantized coefficients. .

  The quantization coefficients to be encoded this time are “+0011”, “+0110”, “0000”, and “−0011”, and the third quantization coefficient “0000” has an absolute value of 0. The entropy encoding unit 123 outputs a code “001” indicating each sign (positive, positive, negative) of the non-zero quantization coefficients “+0011”, “+0110”, and “−0011”.

  When the four quantization coefficients “+0011”, “+0110”, “0000”, and “−0011” are encoded, the entropy encoding unit 123 further performs the following four quantization coefficients “+1101”. "," -0100 "," +0111 ", and" -1010 "are encoded.

  First, the entropy encoding unit 123 compares the maximum number of significant digits of the newly input four (w) quantized coefficients with the maximum number of significant digits of the four previously encoded quantized coefficients. To do.

  The maximum number of significant digits of the four (w) quantized coefficients “+1101”, “-0100”, “+0111”, and “-1010” input this time is the quantized coefficient “ The entropy encoding unit 123 uses the maximum number of significant digits as “4”, which is the first digit of +1101 ”, which is different from the maximum number of significant digits“ 3 ”of the previously encoded quantization coefficient. 1 is output indicating that has changed.

  Also, since the previous maximum number of significant digits is 3 and the current maximum number of significant digits is 4, the entropy encoding unit 123 indicates that the maximum number of significant digits has increased as shown on the right side in the figure. The indicated code 0 is output.

  Furthermore, the entropy encoding unit 123 outputs a code indicating how much the maximum number of significant digits has increased or decreased. In this case, since the amount of change in the maximum number of significant digits is 1 (= 4-3), the entropy encoding unit 123 outputs 0 (= 1-1) 0s and further 1s as codes. (In other words, code 1 is output).

  Next, the entropy encoding unit 123 calculates the absolute values of the four (w) quantized coefficients “+1101”, “-0100”, “+0111”, and “-1010” to be encoded this time. A code “1101010001111010” in which codes “1101”, “0100”, “0111”, and “1010” corresponding to the maximum number of significant digits shown are sequentially arranged is output.

  When a code indicating the absolute value of the quantized coefficient is output, the entropy encoding unit 123 outputs a code indicating the sign of each quantized coefficient that is not 0 among the four quantized coefficients.

  The quantization coefficients to be encoded this time are “+1101”, “-0100”, “+0111”, and “-1010”, and the signs of these quantization coefficients are positive, negative, positive, negative in order. Therefore, as shown in the lower right in the figure, the entropy encoding unit 123 outputs “0101” as a code indicating each sign of the quantized coefficient.

  In this way, the entropy encoding unit 123 encodes the input quantization coefficient by a predetermined number (w) in succession. As a result, the entropy encoding unit 123 outputs a code indicating whether or not the quantization coefficients of the line to be encoded are all 0, and outputs a code indicating that the quantization coefficients of the line are not all 0. Then, a code indicating the maximum number of significant digits of w quantized coefficients, a code indicating the absolute value (bit plane representation) of w quantized coefficients, and a code indicating the sign of those quantized coefficients Is output.

  Each of the code indicating the maximum number of significant digits of the w quantized coefficients, the code indicating the absolute value of the w quantized coefficients, and the code indicating the sign of the quantized coefficient is the quantization of the line. Until all the coefficients are encoded, a code indicating the maximum number of significant digits of the next w quantized coefficients, a code indicating the absolute value of the quantized coefficient, and a code indicating the sign of the quantized coefficient are repeatedly output. .

  Although it has been described that the quantized coefficients are encoded in the raster scan order, the order in which the quantized coefficients are encoded does not necessarily have to be the raster scan order. For example, if the subband quantized coefficients shown in FIG. 20 are encoded, first the positions (0,0), (0,1), (0,2), and (0,3) (ie, The quantized coefficients at the leftmost position in each of the lines L1 to L4 are encoded, and then the positions (1, 0), (1, 1), (1, 2), and (1, 2, In the figure, the quantized coefficients at 4 positions in the vertical direction in the figure are coded as w quantized coefficients, so that the w coefficients are sequentially coded. Good.

  More specifically, the entropy encoding unit 123 of FIG. 1 that performs the processing described above is configured as shown in FIG.

  The entropy encoding unit 123 includes a line determination unit 161, a VLC (Variable Length Coding) encoding unit 162, a maximum significant digit calculation unit 163, a VLC encoding unit 164, an effective digit extraction unit 165, a VLC encoding unit 166, a sign An extraction unit 167, a VLC encoding unit 168, and a code concatenation unit 169 are included.

  The quantization coefficient output from the quantization unit 122 (FIG. 19) is supplied (input) to the line determination unit 161, the maximum significant digit number calculation unit 163, the significant digit extraction unit 165, and the sine extraction unit 167.

  The line determination unit 161 determines whether or not the quantization coefficients of one line to be encoded input from the quantization unit 122 are all 0, and displays information indicating the determination result as VLC encoding unit Supply to 162.

  Based on the information indicating the determination result from line determination unit 161, VLC encoding unit 162 outputs a code indicating whether or not the quantization coefficients of the lines to be encoded are all 0 to code concatenation unit 169. .

  Maximum number of significant digits calculation unit 163 calculates the maximum number of significant digits of continuous w quantized coefficients input from quantization unit 122, and provides information indicating the result of the calculation to VLC encoding unit 164 and effective number of digits. This is supplied to the digit extraction unit 165.

  The VLC encoding unit 164 supplies a code indicating the maximum number of significant digits of the w quantized coefficients to the code concatenation unit 169 based on the information indicating the calculation result from the maximum number of significant digits calculation unit 163.

  The significant digit extraction unit 165 extracts the significant digits of the w quantization coefficients supplied from the quantization unit 122 based on the information indicating the calculation result from the maximum number of significant digits calculation unit 163, and extracts the extracted quantum The significant digit (data) of the quantization coefficient is supplied to the VLC encoding unit 166 and the sign extraction unit 167.

  The VLC encoding unit 166 encodes absolute values of these quantized coefficients based on the significant digits of the quantized coefficients from the effective digit extracting unit 165, and a code indicating the absolute values of the quantized coefficients obtained thereby. Is supplied to the code connecting unit 169.

  The sine extraction unit 167 extracts the sine of the quantization coefficient supplied from the quantization unit 122 based on the significant digit of the quantization coefficient from the significant digit extraction unit 165, and extracts the extracted sine (data) from the VLC. This is supplied to the encoding unit 168.

  The VLC encoding unit 168 encodes the sine (data) from the sine extraction unit 167 and supplies a code indicating the sign of the quantized coefficient obtained thereby to the code concatenation unit 169.

  The code concatenation unit 169 determines whether or not the line quantization coefficients supplied from the VLC encoding unit 162, the VLC encoding unit 164, the VLC encoding unit 166, and the VLC encoding unit 168 are all 0. , A code indicating the maximum number of significant digits, a code indicating the absolute value of the quantized coefficient, and a code indicating the sign of the quantized coefficient are connected and output as an encoded image (data).

  Next, encoding processing by the image encoding device 111 (FIG. 19) will be described with reference to the flowchart in FIG. This encoding process is started when an image (data) to be encoded is input to the wavelet transform unit 121.

  In step S111, the wavelet transform unit 121 performs wavelet transform on the input image, decomposes the input image into a plurality of subbands, and supplies the wavelet coefficients of each subband to the quantization unit 122.

  In step S112, the quantization unit 122 quantizes the wavelet coefficients supplied from the wavelet transform unit 121, and supplies the quantization coefficients obtained as a result to the entropy encoding unit 123. As a result, the entropy encoding unit 123 receives, for example, the quantization coefficient at each position of the subband expressed in the bit plane described with reference to FIG.

  In step S113, the entropy encoding unit 123 performs entropy encoding processing, and ends the encoding processing. Although details of the entropy encoding process will be described later, the entropy encoding unit 123 determines the quantization coefficient supplied from the quantization unit 122 in the entropy encoding process as described with reference to FIG. Code indicating the number of quantization coefficients of the line to be encoded, whether the quantization coefficient of the line to be encoded is all 0, a code indicating the maximum number of significant digits of the quantization coefficient, and the absolute value of the quantization coefficient The code and the code indicating the sign of the quantization coefficient are output as an encoded image (data).

  In this way, the image encoding device 111 encodes and outputs the input image.

  Next, the entropy encoding process corresponding to the process of step S113 of FIG. 23 will be described with reference to the flowchart of FIG.

  In step S112 of FIG. 23, the quantized coefficients output from the quantization unit 122 are the line determination unit 161, the maximum significant digit number calculation unit 163, the significant digit extraction unit 165, and the entropy coding unit 123 (FIG. 22). It is supplied (input) to the sign extraction unit 167.

  In step S141, the line determination unit 161 stores a variable y indicating a subband line to be encoded as y = 0.

  For example, when the subband quantization coefficient shown in FIG. 20 is encoded, the line determination unit 161 sets y = 0 as a variable y indicating the line (line L1 to line L6) of the subband. Here, the line y indicated by the variable y indicates a line where the y coordinate at each position (x, y) on the subband line is y. Therefore, for example, when the variable y stored in the line determination unit 161 is y = 0, the line indicated by the variable is a line L1 in which the y coordinate at each position on the line is 0.

  In step S142, the maximum number of significant digits calculation unit 163 first inputs w pieces on the line (y-1) immediately before the line y indicated by the variable y stored in the line determination unit 161. The variable Binit indicating the maximum number of significant digits of the quantization coefficient is set as Binit = 0 and stored.

  For example, if the line (y−1) is the line L1 shown in FIG. 20, the variable Binit indicating the maximum number of significant digits of w quantized coefficients input first on the line (y−1) The value is w quantization coefficients from the leftmost position in the diagram of the line L1, that is, w number of positions (0, 0), (1, 0), ..., (w-1, 0). This is the maximum number of significant digits of the quantization coefficient. Further, when the variable y stored in the line determination unit 161 is y = 0, the line (y−1) does not exist, so the value of the variable Binit is set to Binit = 0.

  In step S143, the line determination unit 161 determines whether or not the quantization coefficients (absolute values) of the line y indicated by the stored variable y are all zero. For example, when the line y is the line L1 illustrated in FIG. 20, the line determination unit 161 determines that the quantization coefficient is all 0 when the quantization coefficient at the position (x, y) on the line L1 is all 0. It is determined that

  If it is determined in step S143 that the quantized coefficients are all 0, the line determining unit 161 generates information indicating that the quantized coefficients are all 0 and outputs the information to the VLC encoding unit 162 and the maximum number of significant digits. The data is supplied to the calculation unit 163, and the process proceeds to step S144.

  In step S144, the VLC encoding unit 162, based on the information indicating that the quantization coefficients are all 0 from the line determination unit 161, the code 0 indicating that the quantization coefficients of the lines to be encoded are all 0. Is output (supplied) to the code connecting unit 169. The code concatenation unit 169 outputs the code 0 supplied from the VLC encoding unit 162 as it is as a code obtained as a result of encoding the quantized coefficient of the line y.

  In step S145, the maximum number of significant digits calculation unit 163 sets the value of the stored variable Binit to Binit = 0 based on the information that the quantization coefficients from the line determination unit 161 are all 0, and sets the variable Binit Update.

  In step S146, the line determination unit 161 determines whether there is an unprocessed line among the encoded subband lines. That is, the line determination unit 161 determines whether or not the quantized coefficients of all lines of the subband being encoded have been encoded. For example, when the subband quantization coefficients illustrated in FIG. 20 are encoded, when the quantization coefficients at all positions on the lines L1 to L6 are encoded, the line determination unit 161 performs unprocessed processing. It is determined that the line does not exist.

  When it is determined in step S146 that there is an unprocessed line, the line determination unit 161 encodes the quantized coefficient at each position on the next line, that is, the line (y + 1), and thus the process is performed in step S147. Proceed to

  In step S147, the line determination unit 161 increments the variable y indicating the stored line to y = y + 1, returns the process to step S143, and causes the subsequent processes described above to be executed again.

  On the other hand, when it is determined in step S146 that there is no unprocessed line, the line determination unit 161 ends the entropy encoding process because the quantization coefficient is encoded for all the lines constituting the subband. Then, the process returns to step S113 in FIG. 23 to end the encoding process.

  Also, in step S143 of FIG. 24, when it is determined that the quantized coefficients of the line y are not all zero (there are non-zero quantized coefficients), the line determining unit 161 has all the quantized coefficients not zero (not zero). Information indicating that a quantized coefficient exists) is generated and supplied to the VLC encoding unit 162 and the maximum number of significant digits calculation unit 163, and the process proceeds to step S148.

  In step S148, the VLC encoding unit 162 encodes code 1 indicating that the quantization coefficients of the line to be encoded are not all 0 based on the information indicating that the quantization coefficients are not all 0 from the line determination unit 161. Output (supply) to the connecting section 169.

  In step S149, based on the information that the quantized coefficients from the line determining unit 161 are not all 0, the maximum significant digit calculating unit 163 is input first among the w quantized coefficients to be encoded. The variable x indicating the x coordinate of the position on the line y corresponding to the quantization coefficient to be set is set to x = 0, and this variable x is stored.

  For example, when the line y is the line L1 shown in FIG. 20, the value of the variable x stored in the maximum number of significant digits calculation unit 163 is the continuous w number of lines on the line L1 to be encoded. Among the positions (x, 0), (x + 1, 0),..., (X + w−1, 0), the x coordinate of the leftmost position (x, 0) is shown.

  In step S149, the maximum significant digit calculation unit 163 stores the variable B with B = Binit as the value of the variable B indicating the maximum number of significant digits of the previously coded w quantization coefficients. That is, the maximum number of significant digits calculation unit 163 updates the variable B as the value of the variable Binit that stores the value of the variable B, and stores the updated value of the variable B.

  When the value of the variable B is updated, the maximum number of significant digits calculation unit 163 supplies information indicating the updated value of the variable B (maximum number of significant digits) to the VLC encoding unit 164 and the significant digit extraction unit 165. In addition, the VLC encoding unit 164 and the significant digit extraction unit 165 store the value of the variable B supplied from the maximum significant digit number calculation unit 163, respectively.

  In step S150, the entropy encoding unit 123 performs w group encoding processing. Although details of the w-piece encoding process will be described later, in the w-piece encoding process, the entropy encoding unit 123 continues the line y indicated by the variable y stored in the line determination unit 161. Encode w quantized coefficients.

  Here, assuming that the position on the line y specified by the variable y stored in the line determination unit 161 and the variable x stored in the maximum number of significant digits calculation unit 163 is (x, y), the line y The upper w consecutive positions are the consecutive positions (x, y), (x + 1, y),..., (X + w−1, y) on the line y. That is, in the w-group encoding process, the entropy encoding unit 123 encodes the respective quantized coefficients at the positions (x, y), (x + 1, y),..., (X + w−1, y). To do.

  In step S151, the maximum number of significant digits calculation unit 163 determines whether or not there is an unprocessed quantization coefficient in the line y. That is, the maximum number of significant digits calculation unit 163 determines whether all the quantized coefficients at the position on the line y indicated by the variable y stored in the line determination unit 161 have been encoded.

  If it is determined in step S151 that there is an unprocessed quantized coefficient in the line y, the maximum significant digit number calculating unit 163 encodes the next w quantized coefficients, and thus the process proceeds to step S152.

  In step S152, the maximum number of significant digits calculation unit 163 sets the stored variable x to x = x + w, and returns the process to step S150. Thus, in the subsequent processing of step S150, the respective quantized coefficients at positions (x + w, y), (x + w + 1, y),..., (X + 2w−1, y) on the line y are encoded. .

  Further, when it is determined in step S151 that there is no unprocessed quantization coefficient on the line y, the maximum number of significant digits calculation unit 163 has encoded the quantization coefficients at all one position on the line y. Then, the process returns to step S146, and the subsequent processes are executed.

  In this way, the entropy encoding unit 123 encodes a predetermined number of quantization coefficients at each position of the subband in the raster scan order.

  In this way, by encoding a predetermined number of quantization coefficients at each position in the subband in the raster scan order, the input quantization coefficients can be processed in the input order, and the quantization coefficient code It is possible to reduce the delay caused by the conversion.

  Next, with reference to the flowchart in FIG. 25, the w-group encoding process corresponding to the process in step S50 in FIG. 24 will be described.

  In step S181, the maximum number of significant digits calculation unit 163 sets the position on the line y specified by the stored variable x as (x, y), w consecutive positions (x, y), (x + 1) , Y),..., (X + w−1, y) of the quantized coefficients having the largest absolute value, the largest significant digit of w quantized coefficients to be encoded. This variable Bnew is stored as the value of the variable Bnew indicating the number.

  Also, the maximum number of significant digits calculation unit 163 supplies the maximum number of significant digits of the obtained w quantization coefficients, that is, the value of the variable Bnew to the VLC encoding unit 164 and the significant digit extraction unit 165.

  For example, if each of the w consecutive position quantization coefficients is the quantization coefficients “-0101”, “+0011”, “-0110”, and “+0010” shown in FIG. Among the quantized coefficients, the quantized coefficient having the maximum absolute value is “-0110”, and the number of significant digits is “3” which is the first digit of “-0110”. The value of is assumed to be 3.

  In step S182, the VLC encoding unit 164 determines whether B = Bnew. That is, the VLC encoding unit 164 stores the value of the variable B indicating the maximum number of significant digits of the previously encoded w quantized coefficients supplied from the maximum number of significant digits calculation unit 163. It is determined whether or not the value of the variable Bnew indicating the maximum number of significant digits of the w quantized coefficients to be encoded is the same.

  If it is determined in step S182 that B = Bnew, the VLC encoding unit 164 proceeds to step S183, and uses the maximum valid code as the code indicating the maximum number of significant digits of w quantization coefficients to be encoded. A code 0 indicating that the number of digits has not changed is output to the code concatenation unit 169. When the code 0 indicating the maximum number of significant digits is output, the VLC encoding unit 164 skips the processing from step S184 to step S188, and proceeds to step S189.

  On the other hand, if it is determined in step S182 that B = Bnew is not satisfied, the VLC encoding unit 164 proceeds to step S184 and changes the maximum number of significant digits (since the maximum number of significant digits has changed). The code 1 indicating this is output to the code linking unit 169.

  In step S185, the VLC encoding unit 164 obtains integers n and m that satisfy the following equation (8).

  Bnew = B + (n + 1) × (−1) ^ m (8)

  Here, the symbol “^” in Equation (8) represents a power. Therefore, (−1) ^ m represents (−1) to the m-th power.

  For example, when Bnew = 3 and B = 0, n = 2 and m = 0 are obtained as n and m satisfying Expression (8), respectively. When the variable Bnew and the variable B are compared, the value of n in the equation (8) increases as the difference between the absolute value of the variable Bnew and the absolute value of the variable B increases. Therefore, it can be said that the value of n indicates the amount of change in the maximum number of significant digits. When the value of the variable Bnew is larger than the value of the variable B, the value of m is 0. Conversely, when the value of the variable Bnew is smaller than the value of the variable B, the value of m is 1. Therefore, it can be said that the value of m in Equation (8) indicates whether the maximum number of significant digits has increased or decreased.

  In step S186, the VLC encoding unit 164 outputs a value of m satisfying Equation (8) to the code concatenation unit 169 as a code indicating whether the maximum number of significant digits has increased or decreased, with a 1-bit code. To do. For example, when the value of m satisfying Equation (8) is 0, the VLC encoding unit 164 outputs code 0 indicating that the maximum number of significant digits has increased.

  In step S187, the VLC encoding unit 164 outputs a single 1 to the code concatenation unit 169 as a code indicating the amount of change in the maximum number of significant digits, followed by a value of n that satisfies Equation (8), followed by 0. To do. That is, VLC encoding section 164 outputs n 0s and 1 1s as codes indicating the change amount of the maximum number of significant digits.

  For example, when the value of n satisfying Expression (8) is 2, the VLC encoding unit 164 outputs “001” to the code concatenation unit 169 as a code indicating the amount of change in the maximum number of significant digits.

  As a result, the VLC encoding unit 164 to the code concatenating unit 169 provide a code indicating that the maximum number of significant digits has changed as a code indicating the maximum number of significant digits of the w quantized coefficients to be encoded. A code indicating whether the number of digits has increased or decreased and a code indicating the amount of change in the maximum number of significant digits are output.

  In step S188, the maximum number of significant digits calculation unit 163 sets the value of the stored variable B to B = Bnew, and advances the process to step S189. That is, the maximum number of significant digits calculation unit 163 updates the variable B with the stored value of the variable B as the stored value of the variable Bnew. In addition, the value of the variable B stored in the VLC encoding unit 164 and the effective digit extraction unit 165 is B = Bnew.

  When the value of the variable B is set to B = Bnew in step S188 or a code indicating the maximum number of significant digits of the quantization coefficient is output in step S183, the maximum number of significant digits calculation unit 163 is output in step S189. If the value of the stored variable x is 0, the stored variable Binit is set to Binit = B.

  That is, when the value of the stored variable x is 0, the maximum number of significant digits calculation unit 163 stores the first input w quantized coefficients on the line (y−1). The variable Binit is updated by setting the value of the variable Binit indicating the maximum number of significant digits as the value of the variable B indicating the maximum number of significant digits of the previously coded w quantization coefficients.

  Thus, when the variable x = 0, the value of the variable Binit is set to Binit = B, so that w quantization coefficients starting from x = 0 of the next line (for example, the line (y + 1)) are obtained. The quantization coefficient can be encoded using the correlation with the maximum number of significant digits of w quantization coefficients starting from x = 0 in the previous line (for example, line y).

  In step S190, the significant digit extraction unit 165 changes the variable i from 0 to (w−1), where i is a predetermined variable, and the position (x + i, Extract the significant digits of the quantization coefficient from the quantization coefficient of y). The effective digit extraction unit 165 supplies the extracted effective digits (data) of the quantized coefficient to the VLC encoding unit 166 and the sign extraction unit 167. Also, the VLC encoding unit 166 adds a code indicating the absolute value of the w quantized coefficients to the code concatenating unit 169 based on the significant digits supplied from the significant digit extracting unit 165 (by encoding the significant digits). Output.

  Here, the value of x at the position (x + i, y) is the value of the variable x stored in the maximum number of significant digits calculation unit 163. For example, the value of the variable x stored in the maximum significant digit calculation unit 163 is 0, the value of the variable B stored in the significant digit extraction unit 165 is 3, and the quantization unit 122 The digit extraction unit 165 receives the quantum of each of the positions (x + i, y) (0 ≦ i ≦ 3), that is, the positions (0, y), (1, y), (2, y), and (3, y). Assuming that w (4) quantization coefficients “-0101”, “+0011”, “-0110”, and “+0010” shown in FIG. 21 corresponding to the quantization coefficient are supplied, the significant digit extraction unit 165 extracts significant digits from these quantized coefficients.

  In this case, since the value of the variable B stored in the significant digit extraction unit 165 is 3 and the significant digits are 3, the significant digit extraction unit 165 calculates the quantization coefficient corresponding to the position (x, y). From “-0101”, extract the three-digit value “101” from the lowest.

  Similarly, the significant digit extraction unit 165 performs quantization coefficients “+0011”, “-0110”, and “+” for the position (x + 1, y), the position (x + 2, y), and the position (x + 3, y), respectively. From “0010”, the three-digit values “011”, “110”, and “010” are extracted sequentially from the lowest order. As a result, the significant digit extraction unit 165, the VLC encoding unit 166, and the sine extraction unit 167 receive the significant digits of the quantization coefficients “-0101”, “+0011”, “-0110”, and “+0010”. Sign) “101”, “011”, “110”, and “010” are output. The VLC encoding unit 166 encodes the codes “101”, “011”, “110”, and “010” supplied from the significant digit extraction unit 165 and calculates the absolute value of w (4) quantization coefficients. The code “101011110010” indicating the value is output to the code coupling unit 169.

  In step S191, the sign extraction unit 167 changes the variable i from 0 to (w−1), where i is a predetermined variable, and the absolute value of the quantization coefficient supplied from the quantization unit 122 is not 0. The sine of the quantized coefficient is extracted from the quantized coefficient at the position (x + i, y) on the line y, and the extracted sine (data) is supplied to the VLC encoding unit 168. The VLC encoding unit 168 encodes the sine from the sine extraction unit 167 and outputs a code indicating the sign of the quantization coefficient obtained thereby to the code connection unit 169.

  When the code indicating the sign of the quantized coefficient is supplied from the VLC encoding unit 168, the code concatenation unit 169 receives the VLC encoding unit 162, the VLC encoding unit 164, the VLC encoding unit 166, and the VLC encoding unit 168. , A code indicating whether the quantization coefficients are all 0, a code indicating the maximum number of significant digits of the quantization coefficient, a code indicating the absolute value of the quantization coefficient, and a sign of the quantization coefficient Are connected, and the connected code is output as an encoded image, the w-piece set encoding process is terminated, the process returns to step S150 in FIG. 24, and the processes after step S151 are performed. Execute.

  Here, the value of x at the position (x + i, y) is the value of the variable x stored in the maximum number of significant digits calculation unit 163. For example, the value of the variable x stored in the maximum number of significant digits calculation unit 163 is 0, and each of the positions (x + i, y) (0 ≦ i ≦ 3) is transferred from the quantization unit 122 to the sine extraction unit 167. That is, the w (4) quantization coefficients “−” shown in FIG. 21 corresponding to the quantization coefficients at the positions (0, y), (1, y), (2, y), and (3, y). Assuming that "0101", "+0011", "-0110", and "+0010" are supplied, the quantization coefficients "-0101", "+0011", "-0110", and "+0010" Since it is not 0, the sine extraction unit 167 extracts a sine from these quantized coefficients.

  In this case, the sign extraction unit 167 extracts the sign “−” of the quantized coefficient from the quantized coefficient “-0101” corresponding to the position (x, y).

  Similarly, the sign extraction unit 167 performs quantization coefficients “+0011”, “-0110”, and “+0010” for the position (x + 1, y), the position (x + 2, y), and the position (x + 3, y), respectively. ”Sequentially extracts the signs“ + ”,“ − ”, and“ + ”of these quantization coefficients. As a result, the sign extraction unit 167 to the VLC encoding unit 168 transfer the signs “−”, “+”, “+” of the quantized coefficients “-0101”, “+0011”, “-0110”, and “+0010”. “-” And “+” are output. The VLC encoding unit 168 encodes the sine “−”, “+”, “−”, and “+” of the quantization coefficient supplied from the sine extraction unit 167.

  For example, the VLC encoding unit 168 outputs the code 1 when the sign “−” is input, and outputs the code 0 when the sign “+” is input, thereby encoding the input sign. In this case, since the sign “−”, “+”, “−”, and “+” of the quantized coefficients are input to the VLC encoding unit 168, the VLC encoding unit 168 includes the code “1”, A code “1010” composed of “0”, “1”, and “0” is output to the code concatenation unit 169 as a code indicating the sign of the quantization coefficient.

  In this way, the entropy encoding unit 123 encodes the predetermined number of subband quantization coefficients in a predetermined amount, and encodes the code indicating the maximum number of significant digits of the quantization coefficient and the absolute value of the quantization coefficient. A code indicating the value and a code indicating the sign of the quantization coefficient are output.

  In this way, by encoding a predetermined number of subband quantization coefficients together in a predetermined number, for example, unlike the case of encoding an image by the JPEG2000 system, it is based on a plurality of coding passes. In addition, since it is not necessary to perform a plurality of processes for each bit plane and variable length encoding is performed, the amount of encoding processing can be greatly reduced. As a result, the image can be encoded at a higher speed, and an encoding device for encoding a high-resolution image in real time can be realized at low cost.

  Further, in the image encoding device 111, when encoding an image, it is not necessary to explicitly encode the length of the code, so the amount of code can be reduced, and information on the length of the code can be stored. There is no need to manage.

  In the above description, among the w quantized coefficients, it has been described that the number of significant digits of the quantized coefficient having the largest absolute value is the value of the variable Bnew indicating the maximum number of significant digits, but the value of the variable Bnew is , Of the w quantized coefficients, it may be a value equal to or greater than the number of significant digits of the quantized coefficient having the largest absolute value. When the value of the variable Bnew increases, the code amount of the code indicating the absolute value of the quantization coefficient increases, but by setting the value of the variable Bnew to a value greater than the number of significant digits of the quantization coefficient having the largest absolute value, Thus, the code amount of the code indicating the maximum number of significant digits of the quantization coefficient can be reduced.

  Next, an image decoding apparatus that decodes an image encoded by the image encoding apparatus 111 will be described.

  FIG. 26 is a block diagram illustrating a configuration example of an image decoding device.

  The image decoding device 211 includes an entropy decoding unit 221, an inverse quantization unit 222, and a wavelet inverse transformation unit 223, and an encoded image (data) is input to the entropy decoding unit 221.

  The entropy decoding unit 221 performs entropy decoding on the input encoded image code and supplies the quantization coefficient obtained thereby to the inverse quantization unit 222.

  The inverse quantization unit 222 inversely quantizes the quantization coefficient supplied from the entropy decoding unit 221 and supplies the wavelet coefficient of each subband obtained by the inverse quantization to the wavelet inverse transformation unit 223.

  The wavelet inverse transform unit 223 performs wavelet inverse transform on the wavelet coefficients of each subband supplied from the inverse quantization unit 222, and outputs the resulting image as a decoded image.

  In addition, the entropy decoding unit 221 of the image decoding apparatus 211 that performs such processing is configured in more detail as shown in FIG. 27, for example.

  More specifically, the entropy decoding unit 221 includes a code division unit 251, a line determination unit 252, a generation unit 253, a VLC decoding unit 254, a VLC decoding unit 255, a VLC decoding unit 256, a quantized coefficient synthesis unit 257, and a switching unit. 258.

  Based on the information supplied from each of the line determination unit 252, the VLC decoding unit 254, the VLC decoding unit 255, and the VLC decoding unit 256, the code dividing unit 251 inputs the code as an encoded image that has been input. The divided codes are supplied to the line determination unit 252, the VLC decoding unit 254, the VLC decoding unit 255, or the VLC decoding unit 256.

  In other words, the code division unit 251 determines that the input code is a code indicating whether or not all the quantized coefficients of one encoded line are 0, and the maximum effective number of encoded w quantized coefficients. The line determination unit 252 and the VLC decoding unit are divided into a code indicating the number of digits, a code indicating the absolute value of the encoded w quantized coefficients, and a code indicating the sign of the encoded quantized coefficient. 254, the VLC decoding unit 255, and the VLC decoding unit 256.

  The line determination unit 252 determines whether or not the quantization coefficients of one line of the encoded subband are all 0 based on the code supplied from the code division unit 251, and the result of the determination is Information to be shown is supplied to the code division unit 251, the generation unit 253, and the VLC decoding unit 254.

  The generation unit 253 generates a code indicating a quantization coefficient which is 0 for one line based on the information indicating the determination result from the line determination unit 252 and supplies the code to the switching unit 258.

  The VLC decoding unit 254 decodes the code indicating the maximum number of significant digits of the encoded w quantized coefficients supplied from the code dividing unit 251 and determines the maximum of the encoded w quantized coefficients. The number of significant digits is obtained, and information indicating the obtained maximum number of significant digits is supplied to the code division unit 251, the VLC decoding unit 255, and the quantization coefficient synthesis unit 257.

  The VLC decoding unit 255 decodes the code indicating the absolute value of the quantized coefficient supplied from the code dividing unit 251 based on the information indicating the maximum number of significant digits from the VLC decoding unit 254, and the obtained w The significant digits (data) of the quantized coefficients are supplied to the VLC decoding unit 256 and the quantized coefficient combining unit 257. Further, the VLC decoding unit 255 supplies information indicating the decoding result of the code indicating the absolute value of the quantization coefficient to the code dividing unit 251.

  The VLC decoding unit 256 decodes the code indicating the sign of the quantization coefficient supplied from the code division unit 251 based on the significant digit of the quantization coefficient supplied from the VLC decoding unit 255, and the quantization obtained thereby The coefficient sine (data) is supplied to the quantized coefficient synthesizer 257. In addition, the VLC decoding unit 256 supplies information indicating the decoding result of the code indicating the sign of the quantized coefficient to the code dividing unit 251.

  Based on the information indicating the maximum number of significant digits from the VLC decoding unit 254, the quantization coefficient synthesizing unit 257 and the quantized coefficient supplied from the VLC decoding unit 255 and the quantization supplied from the VLC decoding unit 256 The sign of the coefficient is synthesized, and w quantized coefficients obtained thereby are supplied to the switching unit 258.

  The switching unit 258 outputs the quantization coefficient from the generation unit 253 or the quantization coefficient synthesis unit 257.

  FIG. 28 is a block diagram showing a more detailed configuration example of the code dividing unit 251. As shown in FIG.

  The code dividing unit 251 includes a control unit 271 and a memory 272. When a code as an encoded image is input, the control unit 271 supplies the input code to the memory 272 and temporarily stores it.

  Then, the control unit 271 temporarily stores in the memory 272 based on information supplied from each of the line determination unit 252, the VLC decoding unit 254, the VLC decoding unit 255, and the VLC decoding unit 256 shown in FIG. Among the codes, a code having a predetermined length is read and supplied to the line determination unit 252, the VLC decoding unit 254, the VLC decoding unit 255, or the VLC decoding unit 256.

  In addition to the configuration example illustrated in FIG. 28, the code division unit 251 may be configured as illustrated in FIG. 29, for example.

  The code division unit 251 illustrated in FIG. 29 includes a control unit 291, a switch 292, and nodes 293-1 to 293-4.

  When the code as the encoded image is input to the code division unit 251, the control unit 291 receives the line determination unit 252, the VLC decoding unit 254, the VLC decoding unit 255, and the VLC decoding unit 256 illustrated in FIG. Based on the information supplied from each, the switch 292 is controlled, and among the input codes, a code having a predetermined length is selected as a line determination unit 252, a VLC decoding unit 254, a VLC decoding unit 255, or a VLC decoding unit 256. To supply.

  That is, each of the nodes 293-1 to 293-4 is connected to the line determination unit 252, the VLC decoding unit 254, the VLC decoding unit 255, and the VLC decoding unit 256, and the control unit 291 One of the nodes 293-1 to 293-4 is selected as the supply destination, and the connection between the switch 292 and the selected node is controlled.

  Since the switch 292 connects the node selected based on the control of the control unit 291 to the input, the code input to the code dividing unit 251 is transmitted through the switch 292 and the node connected to the switch 292. The data is supplied to the line determination unit 252, the VLC decoding unit 254, the VLC decoding unit 255, or the VLC decoding unit 256 selected as the supply destination.

  Next, decoding processing by the image decoding device 211 will be described with reference to the flowchart in FIG. This decoding process is started when a code as an encoded image is input to the entropy decoding unit 221.

  In step S231, the entropy decoding unit 221 performs entropy decoding processing, entropy decodes the code as the input image, and supplies the quantization coefficient obtained thereby to the inverse quantization unit 222. Although details of the entropy decoding process will be described later, in this entropy decoding process, the entropy decoding unit 221 decodes the quantized coefficients at consecutive positions on the encoded subband line by w and decodes them. The quantized coefficients are supplied to the inverse quantization unit 222.

  In step S232, the inverse quantization unit 222 inversely quantizes the quantization coefficient supplied from the entropy decoding unit 221 and supplies the wavelet coefficient of each subband obtained by the inverse quantization to the wavelet inverse transformation unit 223.

  In step S233, the wavelet inverse transform unit 223 performs wavelet inverse transform on the wavelet coefficients of each subband supplied from the inverse quantization unit 222, outputs the resulting image, and the decoding process ends.

  In this way, the image decoding device 211 decodes and outputs the encoded image.

  Next, the entropy decoding process corresponding to the process of step S231 of FIG. 30 will be described with reference to the flowchart of FIG.

  In step S261, the line determination unit 252 stores a variable y indicating a subband line to be decoded as y = 0.

  In step S262, the VLC decoding unit 254 first inputs w quantizations on the line (y−1) before the line y indicated by the variable y stored in the line determination unit 252. A variable Binit indicating the maximum number of significant digits of the coefficient is set as Binit = 0 and stored.

  For example, if the line (y−1) is the line L1 shown in FIG. 20, the variable Binit indicating the maximum number of significant digits of w quantized coefficients input first on the line (y−1) The value is the maximum number of significant digits of w quantization coefficients from the leftmost position in the diagram of line L1. Further, when the variable y stored in the line determination unit 152 is y = 0, the line (y−1) does not exist, so the value of the variable Binit is Binit = 0.

  In step S262, the code dividing unit 251 performs line determination using the first 1-bit code of the input codes as a code indicating whether or not all the quantization coefficients of the line to be decoded are 0. Supplied to part 252.

  In step S263, the line determination unit 252 determines whether the 1-bit code read (supplied) from the code division unit 251 is 0, generates information indicating the determination result, and generates the generation unit 253, the VLC decoding unit 254, and the code division unit 251.

  If it is determined in step S263 that the code is 0, since all the quantized coefficients of line y are 0, the line determination unit 252 advances the processing to step S264. In step S264, the generation unit 253 sets all the quantization coefficients of the line y to 0 based on the information indicating the determination result from the line determination unit 252. Then, the generation unit 253 generates a code indicating the quantization coefficient of the line y and supplies the code to the switching unit 258.

  For example, as shown in FIG. 21, when one quantization coefficient is represented by 4 digits and one line has 5 quantization coefficients, the generation unit 253 indicates the quantization coefficient of the line y. As a code, 20 (= 4 × 5) 0s are generated and supplied to the switching unit 258. The switching unit 258 outputs the 20 consecutive 0s supplied from the generation unit 253 to the inverse quantization unit 222 as a code indicating the quantization coefficient of one line.

  In step S265, the VLC decoding unit 254 sets the value of the stored variable Binit to Binit = 0 based on the information indicating the determination result from the line determination unit 252, and updates the variable Binit.

  In step S266, the line determination unit 252 determines whether there is an unprocessed line among the subband lines being decoded. That is, the line determination unit 252 determines whether or not the quantized coefficients at positions on all lines of the subband being decoded have been decoded.

  If it is determined in step S266 that there is an unprocessed line, the line determination unit 252 determines the quantization coefficient at each position on the line (y + 1) next to the line y indicated by the variable y stored by itself. Therefore, the process proceeds to step S267.

  In step S267, the line determination unit 252 increments the variable y indicating the stored line to y = y + 1, returns the process to step S263, and executes the subsequent processes.

  On the other hand, if it is determined in step S266 that there is no unprocessed line, the quantization coefficient is decoded for all the lines constituting the subband, so the line determination unit 252 ends the entropy decoding process. Then, the process returns to step S231 in FIG. 30, and the processes after step S232 are executed.

  If it is determined in step S263 of FIG. 31 that the code is not 0, the line determination unit 252 advances the process to step S268. In step S268, the VLC decoding unit 254, based on the information indicating the determination result from the line determination unit 252, the line corresponding to the first input quantized coefficient among the w quantized coefficients to be decoded from now on. The variable x indicating the x coordinate of the position on y is set to x = 0, and this variable x is stored.

  In step S268, the VLC decoding unit 254 stores the variable B with B = Binit as the value of the variable B indicating the maximum number of significant digits of w quantized coefficients decoded last time. That is, the VLC decoding unit 254 updates the variable B as the value of the variable Binit that stores the value of the variable B, and stores the updated value of the variable B.

  Further, in step S268, the code division unit 251 performs w quantization coefficients for decoding the next 1-bit code of the input code based on the information indicating the determination result from the line determination unit 252. Is supplied to the VLC decoding unit 254 as a code indicating whether or not the maximum number of significant digits has changed.

  In step S269, the entropy decoding unit 221 performs a w-group decoding process. The details of the w-group decoding process will be described later. In this w-group decoding process, the entropy decoding unit 221 uses the continuous w pieces on the line y indicated by the variable y stored in the line determination unit 252. The quantized coefficient at the position of is decoded.

  In step S270, the VLC decoding unit 254 determines whether there is an unprocessed quantized coefficient in the line y. That is, the VLC decoding unit 254 determines whether all quantized coefficients at the position on the line y indicated by the variable y stored in the line determination unit 252 have been decoded.

  If it is determined in step S270 that there is an unprocessed quantized coefficient in the line y, the next w quantized coefficients are decoded, and the VLC decoding unit 254 advances the process to step S271.

  In step S271, the VLC decoding unit 254 sets the stored variable x to x = x + w, and returns the process to step S269. Thereby, in the subsequent processing of step S269, the respective quantized coefficients at positions (x + w, y), (x + w + 1, y),..., (X + 2w−1, y) on the line y are decoded.

  If it is determined in step S270 that there is no unprocessed quantized coefficient on line y, VLC decoding section 254 has decoded the quantized coefficients at all positions on line y, and the process proceeds to step S266. Return and execute the subsequent processing.

  In this way, the entropy decoding unit 221 decodes a predetermined number of quantization coefficients at each position in the subband in the raster scan order.

  In this way, by decoding a predetermined number of quantized coefficients at each position in the subband in the raster scan order, the encoded quantized coefficients can be processed in the input order. The delay caused by decoding can be reduced.

  Next, a w-group decoding process corresponding to the process of step S269 of FIG. 31 will be described with reference to the flowchart of FIG.

  As described above, in step S268 in FIG. 31, the code division unit 251 to the VLC decoding unit 254 indicate a 1-bit code indicating whether or not the maximum number of significant digits of w quantized coefficients to be decoded has changed. Is supplied.

  In step S311 of FIG. 32, the VLC decoding unit 254 determines whether or not the read (supplied) 1-bit code is 0.

  If it is determined in step S311 that the read code is 0, since the maximum number of significant digits has not changed, the VLC decoding unit 254 generates information indicating that the maximum number of significant digits has not changed, and Are supplied to the code division unit 251, the VLC decoding unit 255, and the quantization coefficient synthesis unit 257, and the processing of step S312 to step S314 is skipped and the processing proceeds to step S315.

  That is, when the code indicating whether or not the maximum number of significant digits has changed is 0, as described with reference to FIG. 21, the 1-bit code 0 indicating whether or not the maximum number of significant digits has changed After that, a code indicating the absolute value of the quantization coefficient is input instead of a code indicating whether the maximum number of significant digits has increased or decreased, and a code indicating the amount of change in the maximum number of significant digits. Each process of steps S312 to S314, which is a process of decoding a code indicating whether the number of significant digits has increased or decreased, and a code indicating the amount of change in the maximum number of significant digits is skipped.

  On the other hand, if it is determined in step S311 that the read 1-bit code is not 0, the maximum number of significant digits has changed, so the VLC decoding unit 254 advances the process to step S312 and starts from the code dividing unit 251. Read 1 bit of the code and store the value as a predetermined variable m.

  In step S313, the VLC decoding unit 254 reads the code from the code division unit 251 until the code becomes 1 (until the code 1 is read), and stores the number of code 0 read so far as a predetermined variable n. For example, when the third code read by the VLC decoding unit 254 from the code dividing unit 251 is 1, that is, when the VLC decoding unit 254 reads the code “001”, the VLC decoding unit 254 sets the code 1 Since the number of code 0 read is 2 before reading, the VLC decoding unit 254 stores 2 which is the number of code 0 read as the value of the variable n.

  In step S314, the VLC decoding unit 254 obtains the value of the variable B indicating the maximum number of significant digits according to the following equation (9), and stores the obtained value of the variable B.

  B = B + (n + 1) x (-1) ^ m (9)

  Here, the left side in Equation (9) represents the value of the newly obtained variable B, and B on the right side represents the value of the stored variable B. In addition, the symbol “^” in Expression (9) represents a power. Therefore, (−1) ^ m represents (−1) to the m-th power.

  The VLC decoding unit 254 calculates equation (9) based on the stored variable B, variable m, and variable n, and updates the stored variable B. When the variable B indicating the maximum number of significant digits is updated, the VLC decoding unit 254 generates information indicating the updated maximum number of significant digits, and the code division unit 251, the VLC decoding unit 255, and the quantization coefficient synthesis unit 257 To supply.

  If the new maximum number of significant digits is obtained in step S314 or if it is determined in step S311 that the read 1-bit code is 0, the VLC decoding unit 254 proceeds to step S315 and stores the stored variable x If the value of is 0, the stored value of the variable Binit is set to Binit = B.

  That is, when the value of the stored variable x is 0, the VLC decoding unit 254 stores the maximum significant digit of the first w quantized coefficients input on the line (y−1). The variable Binit is updated with the value of the variable Binit indicating the number as the value of the variable B indicating the maximum number of significant digits of the w quantized coefficients to be decoded.

  Thus, when the variable x = 0, the value of the variable Binit is set to Binit = B, so that w quantization coefficients starting from x = 0 of the next line (for example, the line (y + 1)) are obtained. The quantization coefficient can be decoded using the correlation with the maximum number of significant digits of w quantization coefficients starting from x = 0 of the previous line (for example, line y).

  In step S316, the VLC decoding unit 255 changes the variable i from 0 to (w−1) with the predetermined variable i, reads the code bit by bit from the code division unit 251, and reads the read B-bit code. Is supplied (output) to the VLC decoding unit 256 and the quantized coefficient synthesizing unit 257 as a code indicating the significant digit of the quantized coefficient at the position (x + i, y) on the line y. Also, the VLC decoding unit 255 generates information indicating the significant digits of the quantized coefficients and supplies the information to the code dividing unit 251.

  Here, the value of x at the position (x + i, y) is the value of the variable x stored in the VLC decoding unit 254. For example, when the value of the variable x stored in the VLC decoding unit 254 is 0 and the value of the variable B stored in the VLC decoding unit 255 is 3, the VLC decoding unit 255 sets the variable i = 0. The 3-bit code is read from the code division unit 251 and the read 3-bit code is output as the significant digit of the quantization coefficient at the position (0, y).

  Similarly, the VLC decoding unit 255 further reads a 3-bit code from the code division unit 251 with the variable i = 1, and outputs the code as a significant digit of the quantized coefficient at the position (1, y). 2 reads the next 3-bit code from the code division unit 251 and outputs the code as a significant digit of the quantization coefficient at the position (2, y), and the variable i = 3 from the code division unit 151 Reads a 3-bit code and outputs the code as the significant digit of the quantized coefficient at position (3, y).

  In step S317, the VLC decoding unit 256 changes the variable i from 0 to (w−1), where i is a predetermined variable, and the significant digit (Q + i, y) of the quantized coefficient at the position (x + i, y) on the line y. If the absolute value is not 0, the code is read from the code dividing unit 251 by 1 bit. Then, the VLC decoding unit 256 decodes the read code, and supplies (outputs) the obtained code to the quantization coefficient synthesis unit 257 as a sign of the quantization coefficient. Further, the VLC decoding unit 256 generates information indicating the sign of the quantized coefficient and supplies the information to the code dividing unit 251.

  Here, the value of x at the position (x + i, y) is the value of the variable x stored in the VLC decoding unit 254. For example, when the value of the variable x stored in the VLC decoding unit 254 is 0 and a valid digit (a code indicating “0”) is supplied from the VLC decoding unit 255, the VLC decoding unit 256 sets the variable i = 0. Is read from the code division unit 251, and if the code is 0, the code indicating the sign "-" of the quantization coefficient at the position (0, y) is supplied to the quantization coefficient synthesis unit 257, If the read code is 1, a code indicating the sign “+” of the quantized coefficient at the position (0, y) is supplied to the quantized coefficient synthesizing unit 257.

  In addition, when the absolute value of the sign (indicating the significant digit) supplied from the VLC decoding unit 255 is 0, the VLC decoding unit 256 has no sign of the quantization coefficient at the position (0, y). The code is not read from the part 251.

  Similarly, when the next significant digit (absolute value) supplied from the VLC decoding unit 255 is not 0, the VLC decoding unit 256 reads a 1-bit code from the code division unit 251 with the variable i = 1, and If the code is 0, the code indicating the sign “−” is supplied to the quantized coefficient synthesis unit 257 if the read code is 1, and the code indicating the sign “+” is supplied.

  Further, if the next significant digit supplied from the VLC decoding unit 255 is not 0, the VLC decoding unit 256 reads a 1-bit code from the code division unit 251 with the variable i = 2, and if the code is 0, If the code indicating the sign “−” is 1, the code indicating the sign “+” is supplied to the quantized coefficient synthesis unit 257. Further, if the next significant digit supplied from the VLC decoding unit 255 is not 0, the VLC decoding unit 256 reads a 1-bit code from the code division unit 251 with the variable i = 3, and if the code is 0, If the code indicating the sign “−” is 1, the code indicating the sign “+” is supplied to the quantized coefficient synthesis unit 257.

  In step S318, the quantization coefficient synthesizing unit 257 synthesizes the significant digits supplied from the VLC decoding unit 255 and the sign supplied from the VLC decoding unit 255, and the quantization coefficient obtained thereby is changed to the switching unit 258. Is output to the inverse quantization unit 222, the w-group decoding process is terminated, the process is returned to step S269 in FIG. 31, and the processes after step S270 are executed.

  For example, the number of digits of the absolute value of the quantization coefficient to be output is predetermined. When the number of digits of the absolute value of the predetermined quantized coefficient to be output is 4 digits and the maximum number of significant digits indicated by the information indicating the maximum number of significant digits from the VLC decoding unit 254 is 3, the VLC decoding unit When the significant digit “101” is supplied from 255 and the code indicating the sign “−” is supplied from the VLC decoding unit 255, the quantization coefficient synthesis unit 257 outputs the quantization coefficient “-0101”.

  That is, the quantization coefficient synthesis unit 257 has four digits of the absolute value of the quantization coefficient and “101” (three digits), so the most significant bit of the significant digit “101” Further, the upper bit is set to 0, and the absolute value of the quantization coefficient is set to “0101” having 4 digits. Further, “-0101” obtained by synthesizing the sign “−” of the quantization coefficient and the absolute value “0101” of the quantization coefficient is output as the quantization coefficient.

  Note that, when the significant digit supplied from the VLC decoding unit 255 is 0, the quantization coefficient synthesis unit 257 outputs a quantization coefficient without a sign. For example, when the number of digits of the predetermined absolute value of the quantized coefficient to be output is 4 digits and the maximum number of significant digits indicated by the information indicating the maximum number of significant digits from the VLC decoding unit 254 is 3, VLC When the significant digit “000” is supplied from the decoding unit 255, the quantization coefficient synthesis unit 257 outputs the quantization coefficient “0000”.

  In this way, the entropy decoding unit 221 decodes the encoded subband quantized coefficients by a predetermined number at a time.

  In this way, by decoding the coded subband quantization coefficients in a predetermined number together, for example, unlike the case of decoding an image by the JPEG2000 system, a plurality of coding passes are used. Based on this, it is not necessary to perform a plurality of processes for each bit plane, and the image can be decoded at a higher speed. Thereby, a decoding device for decoding a high-resolution image in real time can be realized at low cost.

  By the way, in the image encoding device 111 described above, when the absolute values of the quantized coefficients are encoded (or decoded), the absolute values of the predetermined w quantized coefficients are sequentially encoded. As described above, w quantization coefficients are encoded simultaneously (in parallel) using a general-purpose DSP (Digital Signal Processor) or a SIMD (Single Instruction Multiple Data) operation instruction used in a general-purpose CPU ( Or, the image can be encoded (or decoded) at a higher speed.

  Here, examples of SIMD operation instructions include MMX (MultiMedia eXtension), SSE (Streaming SIMD Extensions), SSE2, and SSE3, which are used in CPUs of Intel Corporation.

  When the absolute value of the quantization coefficient is encoded using such a SIMD operation instruction, the entropy encoding unit 123 of the image encoding device 111 is configured as shown in FIG. 33, for example.

  The entropy encoding unit 123 illustrated in FIG. 33 includes a line determination unit 161, a VLC encoding unit 162, a maximum significant digit number calculation unit 163, a VLC encoding unit 164, an effective digit extraction unit 165, a VLC encoding unit 166, and a sign extraction 22 is the same as the entropy encoding unit 123 shown in FIG. 22 in that a unit 167 and a VLC encoding unit 168 are provided, and is different in that a buffer 401 is newly provided in the code concatenation unit 169. In FIG. 33, portions corresponding to those in FIG. 22 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  In the buffer 401 of the code concatenation unit 169, the line quantization coefficients supplied from the VLC encoding unit 162, the VLC encoding unit 164, the VLC encoding unit 166, and the VLC encoding unit 168 are all 0. Each of a code indicating whether there is a code, a code indicating the maximum number of significant digits, a code indicating the absolute value of the quantization coefficient, and a code indicating the sign of the quantization coefficient are temporarily stored.

  The storage area of the buffer 401 is managed every 32 bits, and the code (data) input to the buffer 401 is divided into a code used for scalar calculation processing and a code used for vector calculation processing and stored. . That is, in one 32-bit storage area, a code used for a scalar calculation process or a code used for a vector calculation process is stored as a code (data) to be temporarily stored.

  In the entropy encoding unit 123 in FIG. 33, the absolute value of the quantized coefficient is encoded in parallel using the SIMD operation instruction, so that a code indicating the absolute value of the quantized coefficient is a code used for vector operation processing. The other codes are codes used for the scalar calculation process.

  In the following description, of the 32-bit storage area provided in the buffer 401, a storage area for storing a code used for scalar calculation processing is also referred to as a scalar area, and a code used for vector calculation processing is stored. This storage area is also referred to as a vector area.

  Next, with reference to FIG. 34, the entropy encoding performed by the entropy encoding unit 123 of FIG. 33 will be described.

  For example, as shown in the upper left of FIG. 34, the twelve quantization coefficients “-0101”, “+0011”, “-0110”, “+0010”, “+0011”, “+0110” shown in FIG. ”,“ 0000 ”,“ −0011 ”,“ +1101 ”,“ −0100 ”,“ +0111 ”, and“ −1010 ”are input to the entropy encoding unit 123 in order.

  Then, as in the case described with reference to FIG. 21, the code concatenation unit 169 of the entropy encoding unit 123 receives a code “1” indicating whether or not the quantization coefficients of the line to be encoded are all zero. ”And the code“ 10001 ”indicating the maximum number of significant digits of the first four input quantization coefficients“ -0101 ”,“ +0011 ”,“ -0110 ”, and“ +0010 ”are supplied.

  A code “110001” consisting of a code “1” indicating whether or not these quantized coefficients are all 0 and a code “10001” indicating the maximum number of significant digits of the quantized coefficients is indicated by an arrow A11. The data is stored in a 32-bit scalar area provided in the buffer 401 of the code concatenation unit 169.

  In the example of FIG. 34, the scalar area is further divided into four 8-bit areas. In the scalar area, the code stored in the area is from left to right in the figure from the upper bit. Stored and stored in order. When a code is stored in one entire scalar area, that is, when a 32-bit code is stored in one scalar area, one new scalar area is provided in the buffer 401, and a new one is added. Codes used for scalar calculation processing are sequentially stored in the provided scalar area.

  When a code “110001” consisting of a code “1” indicating whether the quantized coefficients are all 0 and a code “10001” indicating the maximum number of significant digits of the quantized coefficients is stored in the scalar area, The entropy encoding unit 123 indicates the absolute values of w (4) quantized coefficients “-0101”, “+0011”, “-0110”, and “+0010” that are input first. The codes for the maximum number of significant digits are stored in the vector area at the same time (arranged in parallel).

  The maximum number of significant digits of the quantization coefficients “-0101”, “+0011”, “-0110”, and “+0010” is “3” as described with reference to FIG. The codes indicating the absolute values of the four quantized coefficients are “101”, “011”, “110”, and “010”, respectively, and as indicated by an arrow A12, the codes indicating the absolute values of the quantized coefficients “ “101”, “011”, “110”, and “010” are stored and stored in parallel in one vector area provided in the buffer 401.

  Here, the vector area is further divided into four 8-bit areas, and each of the four areas of the vector area indicates the absolute value of four quantization coefficients having the same length (bit length). Each of the codes is stored and stored in order from the upper bit from left to right in the figure.

  In the vector area indicated by the arrow A12, a code “101” indicating the absolute value of the quantization coefficient is stored from the left in the 8-bit area on the left side of the figure, and a code “101” is stored in the second 8-bit area from the left. “011” is stored from the left side, the code “110” is stored from the left side in the second area from the right, and the code “010” is stored from the left side and stored in the rightmost area.

  Similarly to the case of the scalar area in the vector area, when a code is stored in one vector area, that is, when a 32-bit code is stored in one vector area, the buffer 401 stores a new code. One vector area is provided, and codes used for vector calculation processing are sequentially stored in the newly provided vector area.

  When the codes indicating the absolute values of the four quantized coefficients “-0101”, “+0011”, “-0110”, and “+0010” are stored in the vector region, the entropy encoding unit 123 uses the arrows As shown in A13, codes indicating the signs of these four quantization coefficients are stored and stored in the scalar area.

  As shown by the arrow A11, in the scalar area, a code “110001” including a code “1” indicating whether or not all the quantized coefficients are 0 and a code “10001” indicating the maximum number of significant digits of the quantized coefficients. "Is already stored, the entropy encoding unit 123 indicates the signs of the quantized coefficients" -0101 "," +0011 "," -0110 ", and" +0010 "as indicated by the arrow A13. The code “1010” is stored and stored on the right side of the already stored code “110001” in the scalar area (following the code “110001”).

  Further, when the first four quantized coefficients are encoded, the entropy encoding unit 123 converts the next four quantized coefficients “+0011”, “+0110”, “0000”, and “−0011”. Encode.

  First, the entropy encoding unit 123 performs the maximum significant digit number “3” of the four quantization coefficients encoded last time, the quantization coefficient “+0011”, “+0110”, “0000”, and Compared with the maximum number of significant digits “3” of “-0011” and the maximum number of significant digits has not changed, the maximum number of significant digits changes as a sign indicating the maximum number of significant digits as shown by arrow A14. The code “0” indicating that the data has not been stored is stored in the scalar area following the code “1100011010” already stored.

  Next, the entropy encoding unit 123 indicates the absolute values of the w (4) quantization coefficients “+0011”, “+0110”, “0000”, and “−0011” input this time. The codes “011”, “110”, “000”, and “011” corresponding to the maximum number of significant digits are simultaneously stored and stored in the vector area as indicated by an arrow A15.

  As shown by arrow A12, in the vector area diagram, the left 8-bit area, the second 8-bit area from the left, the second 8-bit area from the right, and the right-most 8-bit area Since each of codes “101”, “011”, “110”, and “010” has already been stored in each of these, the entropy encoding unit 123 is input this time as indicated by an arrow A15. The codes “011”, “110”, “000”, and “011” indicating the absolute values of the quantized coefficients are respectively stored in the codes “101”, “011”, “110”, And “010” are stored and stored on the right side of each.

  Further, as indicated by arrow A16, the entropy encoding unit 123 has an absolute value among the four quantization coefficients “+0011”, “+0110”, “0000”, and “−0011” input this time. A code “001” indicating the sign of a non-zero quantized coefficient is stored and stored on the right side of the code “11000110100” already stored in the scalar area.

  Then, when the four quantized coefficients “+0011”, “+0110”, “0000”, and “−0011” are encoded, the entropy encoding unit 123 performs the following four quantized coefficients “+1101” "," -0100 "," +0111 ", and" -1010 "are encoded.

  First, the entropy encoding unit 123 sets the maximum number of significant digits “4” of the four quantization coefficients “+1101”, “−0100”, “+0111”, and “−1010” input this time and the previous code. The four quantized coefficients “3” are compared with each other, as shown by an arrow A17, a code “1” indicating that the maximum number of significant digits has changed, and a code “0” indicating that the maximum number of significant digits has increased. A code “101” indicating the maximum number of significant digits consisting of “0” and a code “1” indicating the change amount of the maximum number of significant digits is stored and stored in the scalar area.

  In this case, since the code “11000110100001” is already stored in the scalar area as indicated by the arrow A16, the entropy encoding unit 123 in the figure of this code “11000110100001” as indicated by the arrow A17. The code “101” indicating the maximum number of significant digits is stored on the right side.

  Furthermore, when codes indicating the maximum number of significant digits of the four quantization coefficients “+1101”, “-0100”, “+0111”, and “−1010” are stored, the entropy encoding unit 123 Each of codes “1101”, “0100”, “0111”, and “1010” indicating the absolute value of the quantized coefficient is simultaneously stored and stored in the vector area as indicated by an arrow A18.

  As shown by arrow A15, in the vector area diagram, the left 8-bit area, the second 8-bit area from the left, the second 8-bit area from the right, and the right-most 8-bit area In each of these, codes “101011”, “011110”, “110000”, and “010011” are already stored, the left 8-bit area, the second 8-bit area from the left, and the right Only the 2-bit code can be stored in each of the second 8-bit area and the rightmost 8-bit area.

  Therefore, the entropy encoding unit 123 secures (provides) a new vector area in the buffer 401 as indicated by an arrow A18, and codes “1101” and “0100” indicating the absolute values of the quantized coefficients input this time. , “0111”, and “1010”, each of the upper two bits of the codes “11”, “01”, “01”, and “10” is replaced with the code “ “101011”, “011110”, “110000”, and “010011” are stored and stored successively on the right side, and codes “1101”, “0100”, “0100” indicating the absolute value of the quantization coefficient input this time 0111 ”and“ 1010 ”, the lower two bits of the codes“ 01 ”,“ 00 ”,“ 11 ”, and“ 10 ”are newly provided in the vector area (indicated by the arrow A18). Of the two vector areas that are displayed, the lower vector area in the figure) Stored in and stored in the left side of each of the left-hand area, the second 8-bit area from the left, the second 8-bit area from the right, and the rightmost 8-bit area.

  When the codes indicating the absolute values of the four quantized coefficients “+1101”, “-0100”, “+0111”, and “−1010” are stored, the entropy encoding unit as shown by an arrow A19 123 stores the code “0101” indicating the sign of the quantized coefficient whose absolute value is not 0 among these four quantized coefficients, following the code “11000110100001101” already stored in the scalar area. And remember.

  In this way, when the input quantized coefficient is encoded, the entropy encoding unit 123, the code stored in the scalar area indicated by the arrow A19, out of the two vector areas indicated by the arrow A19 In the figure, the code stored in the upper vector area and the code stored in the lower vector area are sequentially output as encoded images.

  In this case, no sign is stored in the 11 bits on the right side of the scalar area indicated by the arrow A19. Also, the left 8-bit area, the second 8-bit area from the left, the second 8-bit area from the right, and the first of the two vector areas indicated by the arrow A19 No code is stored in the 6-bit area on the right side of each 8-bit area on the right side.

  In this way, when the codes stored and stored in the scalar area and the vector area are output as an encoded image, the scalar area and the vector are encoded at the time when the input quantized coefficients are encoded. When there is an area where no code is stored in the area, an arbitrary code such as “0” is stored and stored in the area where the code is not stored, and then stored in the scalar area and the vector area. Are output as an encoded image.

  Thus, for example, in the example shown by the arrow A19, as an encoded image, the code “11000110100001101010100000000000” stored in the scalar region, the code “10101111011110011100000101001110” stored in the upper vector region in the figure, and the lower image The code “01000000000000001100000010000000” stored in the vector area is output in order. Here, any code stored in the area where the code was not stored at the time of completion of encoding of the quantized coefficient in the scalar area and the vector area is not read at the time of decoding. Various codes may be stored.

  Even when the absolute value of the quantization coefficient is encoded using the SIMD operation instruction, the image encoding device 111 performs the encoding process described with reference to the flowchart of FIG. 23 when an image is input. . Also, in the entropy encoding process of FIG. 24 corresponding to the process of step S113 of FIG. 23, the processes of steps S141 to S149, the process of step S151, and the process of step S152 of FIG. The apparatus 111 performs the same process as the case where the SIMD operation instruction is not used (the process described with reference to FIG. 24), and the case where the SIMD operation instruction is not used in the w-piece encoding process corresponding to step S150. Does a different process.

  Hereinafter, with reference to the flowchart of FIG. 35, a description will be given of the w-piece encoding process when the image encoding apparatus 111 encodes the absolute value of the quantized coefficient using the SIMD operation instruction. Note that the processes in steps S411 to S419 correspond to the processes in steps S181 to S189 in FIG. 25 and are executed in the same manner. Therefore, those descriptions will be repeated and will be omitted.

  Further, when encoding the absolute value of the quantization coefficient using a SIMD operation instruction, in the processing described with reference to FIG. 24 or FIG. 35, supplied from the VLC encoding unit 162 to the code concatenation unit 169, A code indicating whether or not the absolute values of the quantized coefficients of the line to be encoded are all 0, a code indicating the maximum number of significant digits of the quantized coefficients supplied from the VLC encoder 164 to the code concatenation unit 169, Each code indicating the sign of the quantized coefficient supplied from the VLC encoder 168 to the code concatenation unit 169 is a scalar provided in the buffer 401 of the code concatenation unit 169, as described with reference to FIG. It is stored and stored in the area.

  In step S420, the significant digit extraction unit 165 supplies the positions (x, y), (x + 1, y),..., (X + w−1) on w consecutive lines y supplied from the quantization unit 122. , Y), the effective digits of the quantization coefficient are extracted simultaneously. The effective digit extraction unit 165 supplies the extracted effective digits of the quantized coefficient to the VLC encoding unit 166 and the sign extraction unit 167. Also, the VLC encoding unit 166 simultaneously generates a code indicating the absolute value of the w quantized coefficients based on the significant digits supplied from the significant digit extraction unit 165 (encodes the significant digits). Output to.

  Here, the value of x at the position (x, y) is the value of the variable x stored in the maximum number of significant digits calculation unit 163, and the value of y is the variable y stored in the line determination unit 161. The value of For example, when the significant digit extraction unit 165 extracts the significant digits “101”, “011”, “110”, and “010” as the significant digits of the quantization coefficient, the VLC encoding unit 166 transfers the code to the code concatenating unit 169. Is supplied with codes “101”, “011”, “110”, and “010” indicating the absolute values of the four quantized coefficients. A code indicating the value is encoded and stored and stored in the vector area as indicated by an arrow A12 in FIG.

  In step S421, the sign extraction unit 167 changes the variable i from 0 to (w−1) with the predetermined variable i, and is supplied from the quantization unit 122 on the line y where the quantization coefficient is not 0. The sine of the quantized coefficient is extracted from the quantized coefficient at the position (x + i, y), and the extracted sine (data) is supplied to the VLC encoding unit 168. Here, the value of x at the position (x, y) is the value of the variable x stored in the maximum number of significant digits calculation unit 163, and the value of y is the variable y stored in the line determination unit 161. The value of

  The VLC encoding unit 168 encodes the sine from the sine extraction unit 167 and outputs a code indicating the sign of the quantization coefficient obtained thereby to the code connection unit 169. Further, as described with reference to FIG. 34, the code concatenation unit 169 stores the code indicating the sign of the quantized coefficient supplied from the VLC encoding unit 168 in the scalar area of the buffer 401 and stores it.

  When the code concatenation unit 169 stores and stores the code indicating the sign of the quantized coefficient in the scalar area of the buffer 401, the code stored in the scalar area of the buffer 401 as described with reference to FIG. , And the code stored in the vector region are concatenated, and the concatenated code is output as an encoded image, the w-piece set encoding process is terminated, and the process returns to step S150 in FIG. The processing after S151 is executed.

  In this way, the entropy encoding unit 123 simultaneously encodes absolute values of a predetermined number of quantization coefficients.

  In conventional entropy coding using the JPEG2000 method, the quantized coefficients are arithmetically coded for each bit plane based on a plurality of coding paths, so it is difficult to perform predetermined processing in entropy coding simultaneously in parallel. However, since the entropy encoding unit 123 does not need to perform complicated processing in units of bit planes, the absolute values of a plurality of quantization coefficients can be encoded simultaneously.

  In this way, by simultaneously encoding the absolute values of a predetermined number of quantization coefficients, a plurality of processes can be performed simultaneously (in parallel), and an image can be encoded at a higher speed.

  In the processing of step S421, it has been described that the sign of w quantized coefficients is sequentially encoded. However, as in the case of encoding the absolute value of the quantized coefficient, a SIMD operation instruction should be used. Thus, the sign of w quantization coefficients may be encoded simultaneously. In this case, each of the codes indicating the signs of w quantized coefficients obtained by encoding is stored in the vector area of the buffer 401 while being divided into w.

  In the buffer 401, one scalar area or vector area is defined as a 32-bit area, and the 32-bit area is further divided into four 8-bit areas. However, one scalar area or vector area is used. The size of can be an arbitrary size. For example, one scalar area or vector area may be a 128-bit area, and the 128-bit area may be divided into eight 16-bit areas for use.

  Furthermore, when decoding an image encoded using a SIMD operation instruction, the code division unit 251 (FIG. 27) of the image decoding device 211 that decodes the image has the configuration shown in FIG. In 272, a code as an encoded image is stored and stored in units of 32 bits as described with reference to FIG.

  When the control unit 271 reads the code from the memory 272 and outputs the code, first, the storage area storing the first 32-bit code is set as the scalar area, and the quantum of the line to be decoded in the order from the top of the scalar area. A code indicating whether or not the absolute values of the quantization coefficients are all 0, a code indicating the maximum number of significant digits of the quantization coefficient, or a code indicating the sign of the quantization coefficient is read and output.

  When the control unit 271 reads a code indicating the absolute value of the quantization coefficient from the memory 272, the control unit 271 stores a 32-bit storage area next to the storage area that is the scalar area of the memory 272 (therefore, the storage area is The code indicating the absolute value of the quantization coefficient is read out from the vector area and output.

  When an image is encoded, when the code indicating the absolute value of the quantized coefficient is first read at the time of decoding, the quantized coefficient must be stored in the 32-bit storage area next to the scalar area. The image is encoded so that a code indicating the absolute value of (a code used for vector calculation) is stored.

  Further, how many bits of the code as an encoded image are divided into storage areas and stored in the memory 272 depends on one scalar area and vector when the image is encoded by the image encoding device 111. It changes depending on how many bits the area is made. That is, the size of each of the plurality of storage areas in the memory 272 in which codes as images are stored separately is the same size as one scalar area and vector area when an image is encoded. The

  Even when the absolute value of the quantized coefficient is decoded using the SIMD operation instruction, the image decoding device 211 performs the decoding process described with reference to the flowchart of FIG. 30 when an encoded image is input. Do. Further, in the entropy decoding process of FIG. 31 corresponding to the process of step S231 of FIG. 30, each of the processes of steps S261 to S268, the process of step S270, and the process of step S271 of FIG. Performs the same processing as when SIMD operation instructions are not used (the processing described with reference to FIG. 31), and in the w-group decoding processing corresponding to step S269, processing that is different from when SIMD operation instructions are not used. I do.

  Hereinafter, with reference to the flowchart of FIG. 36, a description will be given of the w-piece decoding process when the image decoding apparatus 211 decodes the absolute value of the quantized coefficient using the SIMD operation instruction.

  Note that the processes in steps S451 to S455 correspond to the processes in steps S311 to S315 in FIG. 32 and are executed in the same manner. Therefore, description thereof will be repeated and will be omitted.

  Further, when the absolute value of the quantization coefficient is decoded using the SIMD operation instruction, the memory 272 of the code dividing unit 251 has, for example, three codes as an image as illustrated by an arrow A19 in FIG. Stored in 32-bit areas. Each of the line determination unit 252, the VLC decoding unit 254, and the VLC decoding unit 256 uses the top region in FIG. 34 as the scalar region among the three 32-bit regions (see FIG. From the left, the code indicating whether the quantized coefficients of the line are all 0, the code indicating the maximum number of significant digits of the quantized coefficient, and the code indicating the sign of the quantized coefficient are sequentially read out. Decrypt.

  In step S456, the VLC decoding unit 255 reads w consecutive B-bit codes from the code dividing unit 251 simultaneously, and reads each of the read B B-bit codes at the position (x, y ), (X + 1, y),..., (X + w−1, y) are supplied (output) to the VLC decoding unit 256 and the quantized coefficient synthesizing unit 257 as codes indicating the significant digits of the quantized coefficients. Also, the VLC decoding unit 255 generates information indicating the significant digits of the quantized coefficients and supplies the information to the code dividing unit 251. Here, the value of x at the position (x, y) is the value of the variable x stored in the VLC decoding unit 254, and the value of y is the value of the variable y stored in the line determination unit 252. Is done.

  For example, the predetermined number w is 4, the value of the variable B is 3, and the memory code 272 of the code dividing unit 251 has three codes 32 as indicated by an arrow A19 in FIG. If divided into bit storage areas and stored, the uppermost 32-bit storage area in FIG. 34 is already a scalar area, and whether the line quantization coefficients are all 0 or not. And the code indicating the maximum number of significant digits of the quantization coefficient have been read, and the code has not yet been read from the next 32-bit storage area (second storage area from the top) Therefore, the VLC decoding unit 155 uses the second storage area from the top as a vector area, the left 8-bit area, the second 8-bit area from the left, and the second 8-bit area from the right. , And the rightmost 8-bit area from the left in the figure, position (x, y), (x + 1 , Y), (x + 2, y), and (x + 3, y), the codes “101”, “011”, “110”, and “010” indicating the significant digits of the quantized coefficients are simultaneously read and output. .

  When the code indicating the significant digits of the w quantized coefficients is supplied to the VLC decoding unit 256 and the quantized coefficient combining unit 257, the processing in step S457 and the processing in step S458 are performed. Is the same as the process of step S317 and the process of step S318 in FIG.

  In this way, the entropy decoding unit 221 simultaneously decodes absolute values of a predetermined number of quantization coefficients.

  Thus, by simultaneously decoding the absolute values of a predetermined number of quantization coefficients, a plurality of processes can be performed simultaneously (in parallel), and an image can be decoded at a higher speed.

  In the process of step S457, it has been described that each of the codes indicating the signs of the w quantized coefficients is sequentially decoded, but each of the codes indicating the signs of the w quantized coefficients is performed by SIMD. You may make it perform simultaneously (in parallel) using an arithmetic instruction.

  As described above, unlike conventional JPEG2000 image encoding (or decoding), since it is not necessary to arithmetically encode the quantization coefficient for each bit plane based on a plurality of coding passes, it is simpler. The image can be encoded (or decoded) at a higher speed by the processing.

  In the conventional JPEG2000 system, processing is performed for each bit plane based on a plurality of coding passes. When these processes are performed, the quantization coefficient is approximately multiplied by the number of bit planes. The coefficient had to be accessed and the amount of processing was large.

  Further, when packetizing an encoded image, the packetization process cannot be started unless the encoding of one image is completely completed, and thus a delay is caused accordingly. Further, in the JPEG2000 system, for example, one packet having a quantized coefficient (encoded) corresponding to a position in a rectangular area composed of sides parallel to the x and y directions on the subband shown in FIG. Therefore, a delay corresponding to the length of the rectangular area in the y direction also occurs. In the conventional JPEG2000 system, such a delay due to encoding occurs, and real-time processing is difficult. Although it was possible to reduce the delay by shortening the length in the y direction of the rectangular area on the subband, in this case, the encoding efficiency is deteriorated.

  On the other hand, in the image encoding device 111, as described above, it is not necessary to arithmetically encode the quantization coefficient for each bit plane based on a plurality of coding passes. , When outputting a code indicating the absolute value of the quantized coefficient, when outputting a code indicating the maximum number of significant digits, and when outputting a code indicating the sign of the quantized coefficient, the quantized coefficient is only accessed. An image can be encoded more easily.

  Note that the code indicating the maximum number of significant digits and the code indicating the sign of the quantization coefficient may be 1 bit or 0 bit, so in practice, when encoding an image, the quantum is approximately twice. An image can be encoded simply by accessing the quantization factor. Further, when decoding an image, it is only necessary to access the quantization coefficient once, so that the image can be decoded more easily and at a higher speed.

  In the image encoding device 111 or the image decoding device 211, the subband quantization coefficients are encoded or decoded in the raster scan order, so there is no need to buffer the quantization coefficients, and the delay due to encoding or decoding is reduced. be able to.

  In addition, YUV4: 2: 2 format images of 1920 pixels wide × 1080 pixels wide were actually encoded and decoded using SIMD operation instructions (however, w = 4). The following results were obtained: was gotten. In the case of encoding, the image was wavelet transformed to perform sub-band decomposition in five stages, and the quantized coefficients obtained by quantizing the wavelet coefficients of each sub-band were encoded. The functional blocks necessary for encoding and decoding (for example, the entropy encoding unit 123 in FIG. 33 and the entropy decoding unit 221 in FIG. 27) and the functional blocks for encoding and decoding an image using the JPEG2000 system are Pentium (registered). This was realized by causing a CPU (clock frequency: 3.0 GHz) called trademark 4 (trademark of Intel Corporation) to execute a predetermined program.

  When an image for one frame is encoded by the conventional JPEG2000 method, the code amount is 291571 bytes, and the time required for encoding is 0.26157 seconds. The time required to decode the encoded image was 0.24718 seconds.

  On the other hand, when an image for one frame is encoded by the entropy encoding unit 123 of FIG. 33, the code amount is 343840 bytes, and the time required for encoding is 0.03453 seconds. . Further, the time required for decoding the encoded image by the entropy decoding unit 221 in FIG. 27 was 0.02750 seconds.

  In many cases, 30 frames are displayed per second in a moving image, so if it can be encoded or decoded in 0.033 (= 1/30) second per frame, the image can be processed in real time. In the JPEG2000 system, the time required for encoding is 0.26157 seconds and the time required for decoding is 0.24718 seconds. Therefore, it is difficult to process an image in real time, but the entropy encoding unit 123 in FIG. When an image is encoded, the time required for encoding is 0.03453 seconds, and the image can be processed almost in real time. In addition, when the image is decoded by the entropy decoding unit 221 in FIG. 27, the time required for decoding is 0.02750 seconds, so that the processing can be sufficiently performed in real time.

  In the above, an example of encoding image data or an example of decoding encoded data obtained by encoding image data has been described. However, the present invention is not limited to image data. The present invention can also be applied when decoding encoded data in which audio data or the like is encoded. For example, when audio data is encoded, a code indicating the maximum number of significant digits of w predetermined numerical values represented by the code input as the audio data, a code indicating the absolute value of those numerical values, and A code indicating a sign is output as encoded audio data.

  Further, the features of the present embodiment will be further described. In the encoding method described in the present embodiment, the quantization coefficient is losslessly encoded. Therefore, for example, by quantizing a higher frequency coefficient with a larger quantization step size in accordance with human visual characteristics, the image quality per generated code amount can be greatly improved. Also, for example, by reducing the quantization step size used in a specific spatial range, the image quality of that spatial range can be improved.

  Furthermore, in the encoding method described in the present embodiment, a code in which significant digits of absolute values are arranged is encoded. Assuming that the significant digit part of the absolute value is sent with VLC encoding, if the number of significant digits of the absolute value is N, a very large VLC with 2 ^ (N * W) entries A table is required (in addition to the processing load and processing time, the amount of memory required to hold the VLC table also increases). On the other hand, in the encoding method described in the present embodiment, it is not necessary to use such a large table (not only the processing load and processing time but also the memory capacity can be reduced).

  Although it is possible to use an arithmetic code having a higher compression ratio than VLC, even when a compression method using arithmetic coding such as JPEG2000 is used, for example, in the case of the coding method described in this embodiment Compared with, the compression rate is not greatly improved. That is, the encoding method described in the present embodiment has a high compression rate while being easy to perform the encoding process.

  Since the encoding method described in the present embodiment encodes the maximum number of significant digits of the absolute value in the set of w coefficients, the generated code is utilized by utilizing the fact that the number of significant digits of adjacent coefficients is similar. The amount can be reduced.

  In addition, since the encoding method described in the present embodiment performs differential encoding when encoding the maximum number of significant digits of the absolute value in the set of w coefficients, the significant digits of adjacent coefficients are also used in this respect. The generated code amount can be reduced by utilizing the fact that the numbers are similar.

  The entropy encoding process performed by the entropy encoding unit 123 and the entropy decoding process performed by the entropy decoding unit 221 according to the sixth embodiment described above are applied to each of the first to fifth embodiments described above. It is possible to further reduce the delay time, power consumption, the amount of buffer memory necessary for the processing, and the like of the entire image encoding processing and image decoding processing. For example, the entropy encoding unit 123 may be applied as the entropy encoding unit 15 of the image encoding device 1 in FIG. 1 (that is, the entropy encoding unit 15 performs the entropy encoding process similarly to the entropy encoding unit 123. Can be executed). Further, for example, the entropy decoding unit 221 may be applied as the entropy decoding unit 21 of the image decoding device 20 of FIG. 9 (that is, the entropy decoding unit 21 performs the entropy decoding process in the same manner as the entropy decoding unit 221). Can be).

  That is, the entropy encoding process of the sixth embodiment is applied to each of the first to fifth embodiments described above, so that the output order of the coefficients from the wavelet transform unit of each embodiment is The amount of generated codes can be reduced by taking advantage of the above characteristics (that is, the number of significant digits of consecutive coefficients is similar). Even when the coefficients are rearranged, the wavelet transform unit performs wavelet transform in units of line blocks, so that there is no significant effect on the feature that the effective digits of consecutive coefficients are similar. The generated code amount of the entropy encoding process does not change greatly.

  As described above, the entropy encoding process according to the sixth embodiment is characterized by the wavelet transform process described in the first to fifth embodiments described above, the characteristics of the coefficient data to be processed, and the expected results. The effects are similar and have high affinity for each other. Therefore, the case where the entropy encoding process according to the present embodiment is applied to the wavelet transform process described in the first to fifth embodiments described above rather than the case where other encoding methods are applied. This can be expected to obtain a greater effect in the entire image encoding process.

  Next, a seventh embodiment of the invention will be described. The seventh embodiment is an example in which the image encoding device and the image decoding device according to the above-described embodiments are applied to a digital triax system.

  Triax system is a single coaxial cable that connects a video camera to a camera control unit or switcher when recording or relaying in a television broadcast station or production studio. In this system, a plurality of signals such as a return video signal and a synchronization signal are superimposed and transmitted, and power is supplied.

  Most conventional triax systems transmit analog signals using the above signals. However, in recent years, with the digitization of the entire system, the digitization of triax systems used in broadcasting stations and the like is progressing.

  In the existing digital triax system, the digital video signal transmitted via the triax cable is an uncompressed video signal. This is because, especially in broadcasting stations, the required specifications for signal delay time are strict, and basically the delay time from imaging to monitor output, for example, is required to be within one field (16.67 msec). . Compression encoding methods such as MPEG2 (Moving Pictures Experts Group 2) and MPEG4 that achieve high compression rates and high image quality require several frames of time to compress and encode video signals and decode compressed video signals. Because of its large size, it was never used in the Triax system.

  As described above, the image encoding and image decoding method according to the present invention has a very short delay time from the input of image data to the output image being obtained within one field time, for example, several lines to several tens lines. It is suitable for use with a system.

  FIG. 37 shows a configuration of an example of a digital triax system to which the image coding and image decoding method according to the present invention can be applied. The transmission unit 500 and the camera control unit 502 are connected via a triax cable (coaxial cable) 501. Transmission of digital video signals and digital audio signals (hereinafter referred to as main line signals) that are actually broadcasted or used as material from the transmission unit 500 to the camera control unit 502, transmission from the camera control unit 502 to the video camera unit 503, The intercom audio signal and the return digital video signal are transmitted via the triax cable 501.

  The transmission unit 500 is built in, for example, a video camera device (not shown). However, the present invention is not limited to this, and the transmission unit 500 may be used as an external device for the video camera device by being connected to the video camera device in a predetermined manner. The camera control unit 502 is a device generally called a CCU (Camera Control Unit), for example.

  Since the digital audio signal has little relation to the gist of the present invention, the description for avoiding complexity is omitted.

  The video camera unit 503 is configured in, for example, a video camera device (not shown) and converts light from a subject incident through an optical system 550 having a lens, a focus mechanism, a zoom mechanism, an iris adjustment mechanism, and the like into a CCD (Charge Coupled The light is received by an image pickup device (not shown) composed of (Device) or the like. The image sensor converts the received light into an electrical signal by photoelectric conversion, and further performs predetermined signal processing to output a baseband digital video signal. This digital video signal is output after being mapped to, for example, an HD-SDI (High Definition-Serial Data Interface) format.

  The video camera unit 503 is connected to a display unit 551 used for monitoring and an intercom 552 for exchanging sound with the outside.

  The transmission unit 500 includes a video signal encoding unit 510 and a video signal decoding unit 511, a digital modulation unit 512 and a digital demodulation unit 513, an amplifier 514 and an amplifier 515, and a video separation / synthesis unit 516.

  In the transmission unit 500, a baseband digital video signal mapped to, for example, an HD-SDI format is supplied from the video camera unit 503. This digital video signal is compression-encoded by a video signal encoding unit 510, is converted into an encoded stream, and is supplied to the digital modulation unit 512. The digital modulation unit 512 modulates the supplied encoded stream into a signal in a format suitable for transmission via the triax cable 501, and outputs the signal. The signal output from the digital modulation unit 512 is supplied to the video separation / synthesis unit 516 via the amplifier 514. The video separation / combination unit 516 sends the supplied signal to the triax cable 501. This signal is received by the camera control unit 502 via the triax cable 501.

  A signal output from the camera control unit 502 is received by the transmission unit 500 via the triax cable 501. The received signal is supplied to the video separation / synthesis unit 516, where the digital video signal portion and other signal portions are separated. The digital video signal portion of the received signal is supplied to the digital demodulator 513 via the amplifier 515, and the signal modulated into a signal in a format suitable for transmission via the triax cable 501 on the camera controller 502 side. Demodulate and restore the encoded stream.

  The encoded stream is supplied to the video signal decoding unit 511, the compression code is decoded, and a baseband digital video signal is obtained. The decoded digital video signal is output after being mapped to the HD-SDI format and supplied to the video camera unit 503 as a return digital video signal. The digital video signal for return is supplied to a display unit 551 connected to the video camera unit 503 and used for a monitor for a photographer.

  The camera control unit 502 includes a video separation / synthesis unit 520, an amplifier 521 and an amplifier 522, a front end unit 523, a digital demodulation unit 524 and a digital modulation unit 525, and a video signal decoding unit 526 and a video signal encoding unit 527. .

  A signal output from the transmission unit 500 is received by the camera control unit 502 via the triax cable 501. The received signal is supplied to the video separation / synthesis unit 520. The video separation / synthesis unit 520 supplies the supplied signal to the digital demodulation unit 524 via the amplifier 521 and the front end unit 523. The front end unit 523 includes a gain control unit that adjusts the gain of the input signal, a filter unit that performs predetermined filter processing on the input signal, and the like.

  The digital demodulator 524 demodulates the signal modulated into a signal in a format suitable for transmission via the triax cable 501 on the transmission unit 500 side, and restores the encoded stream. This encoded stream is supplied to the video signal decoding unit 526, where the compression code is decoded and converted into a baseband digital video signal. The decoded digital video signal is output after being mapped to the HD-SDI format and output to the outside as a main line signal.

  A return digital video signal and a digital audio signal are supplied to the camera control unit 502 from the outside. For example, the digital audio signal is supplied to the photographer's income 552 and used to transmit a voice instruction to the photographer from the outside.

  The digital video signal for return is supplied to the video signal encoding unit 527, compression encoded, and supplied to the digital modulation unit 525. The digital modulation unit 525 modulates the supplied encoded stream into a signal in a format suitable for transmission via the triax cable 501, and outputs the modulated signal. The signal output from the digital modulation unit 525 is supplied to the video separation / synthesis unit 520 via the front end unit 523 and the amplifier 522. The video separation / synthesis unit 520 multiplexes this signal with other signals, Send to triax cable 501. This signal is received by the video camera unit 503 via the triax cable 501.

  In the seventh embodiment of the present invention, the above-described embodiments are applied to the video signal encoding unit 510 and the video signal encoding unit 527, and the video signal decoding unit 511 and the video signal decoding unit 526 described above. The image encoding device and the image decoding device described in the above are applied.

  In particular, in the second embodiment of the invention in which the processing of each element in the image encoding device and the image decoding device is performed in parallel, the video captured by the video camera unit 503 is output from the camera control unit 502. Used in the seventh embodiment of the present invention, and the delay of the return digital video signal supplied from the outside and transmitted from the camera control unit 502 to the video camera unit 503 can be suppressed. It is preferable.

  In the case of the system illustrated in FIG. 37, it is considered that the signal processing capability and the memory capacity can be appropriately set in each of the transmission unit 500 and the camera control unit 502. The position to be performed may be on either the transmission unit 500 side or the camera control unit 502 side, and the position on which entropy encoding is performed may be either before or after the rearrangement process.

  That is, on the transmission unit 500 side, the video signal encoding unit 510 performs wavelet transform and entropy encoding on the supplied digital video signal according to the method of the present invention, and outputs an encoded stream. As described above, video signal encoding section 510 starts wavelet transformation when the number of lines corresponding to the number of filter taps used for wavelet transformation and the number of wavelet transformation decomposition levels is input. As described with reference to FIG. 5, FIG. 6, FIG. 11, and the like, when the coefficient data necessary for each element is accumulated in the image encoding device and the image decoding device, the processing by each element is sequentially performed. Is called. When the processing is completed up to the bottom line of one frame or one field, processing of the next one frame or one field is started.

  The same applies when a digital video signal for return is transmitted from the camera control unit 502 side to the transmission unit 500 side. That is, on the camera control unit 502 side, the video signal encoding unit 527 performs wavelet transform and entropy encoding on the return digital video signal supplied from the outside according to the method of the present invention, and generates an encoded stream. Output.

  Here, in many cases, the return digital video signal may have a lower image quality than the digital video signal of the main line signal. Therefore, the video signal encoding unit 527 may reduce the bit rate at the time of encoding. For example, in the video signal encoding unit 527, the rate control unit 14 performs control so that the entropy encoding process in the entropy encoding unit 15 is performed until a lower bit rate is achieved. Further, for example, on the camera control unit 502 side, the video signal encoding unit 527 performs conversion processing to a higher decomposition level in the wavelet transform unit 10, and on the transmission unit 500 side, in the wavelet inverse transform unit 23 of the video signal decoding unit 511 A method of stopping the wavelet inverse transformation to a lower decomposition level is also conceivable. The processing in the video signal encoding unit 527 on the camera control unit 502 side is not limited to this example, and it is conceivable that the decomposition level in the wavelet transform is further reduced to reduce the burden of the conversion processing.

  Next, an eighth embodiment of the present invention will be described. In the eighth embodiment of the present invention, transmission of encoded data encoded by the image encoding device according to the present invention to the image decoding device side is performed using wireless communication. FIG. 38 shows a configuration of an example of a wireless transmission system according to the eighth embodiment of the present invention. In the example of FIG. 38, the video signal is unidirectionally transmitted from the video camera or transmission unit 600 (hereinafter abbreviated as transmission unit 600) side to the reception device 601 side. Audio signals and other signals can be transmitted bidirectionally between the transmission unit 600 and the reception device 601.

  The transmission unit 600 is built in a video camera device (not shown) having a video camera unit 602, for example. Not limited to this, the transmission unit 600 may be used as an external device for the video camera device having the video camera unit 602 and connected to the video camera device in a predetermined manner.

  The video camera unit 602 includes, for example, a predetermined optical system, an image sensor made of, for example, a CCD, and a signal processing unit that outputs a signal output from the image sensor as a digital video signal. From the video camera unit 602, a digital video signal is output after being mapped to, for example, an HD-SDI format. This is not limited to this example, and the digital video signal output from the video camera unit 602 may have another format.

  The transmission unit 600 includes a video signal encoding unit 610, a digital modulation unit 611, and a wireless module unit 612. In the transmission unit 600, a baseband digital video signal is mapped and output from the video camera unit 602 to, for example, an HD-SDI format. This digital video signal is compression-encoded by wavelet transform and entropy encoding by the video signal encoding unit 610 by the compression encoding method according to the present invention, and is supplied as an encoded stream to the digital modulation unit 611. The digital modulation unit 611 digitally modulates the supplied encoded stream into a signal in a format suitable for wireless communication and outputs the signal.

  The digital modulation unit 611 is also supplied with a digital audio signal and other signals such as predetermined commands and data. For example, the video camera unit 602 includes a microphone, converts collected sound into an audio signal, further A / D converts the audio signal, and outputs it as a digital audio signal. The video camera unit 602 can output predetermined commands and data. Commands and data may be generated inside the video camera unit 602, or an operation unit is provided in the video camera unit 602 so that commands and data are generated according to user operations on the operation unit. Also good. An input device for inputting commands and data may be connected to the video camera unit 602.

  The digital modulation unit 611 digitally modulates these digital audio signals and other signals and outputs them. The digital modulation signal output from the digital modulation unit 611 is supplied to the wireless module unit 612 and wirelessly transmitted as a radio wave from the antenna 613.

  Note that, upon receiving an automatic retransmission request (ARQ: Auto Repeat Request) from the receiving apparatus 601 side, the wireless module unit 612 notifies the digital modulation unit 611 of this ARQ and requests data retransmission.

  The radio wave transmitted from the antenna 613 is received by the antenna 620 on the receiving device 601 side and supplied to the wireless module unit 621. The wireless module unit 621 supplies a digital modulation signal based on the received radio wave to the front end unit 622. The front end unit 622 performs predetermined signal processing such as gain control on the supplied digital modulation signal and supplies the digital modulation signal to the digital demodulation unit 623. The digital demodulation unit 623 demodulates the supplied digital modulation signal and restores the encoded stream.

  The encoded stream restored by the digital demodulating unit 623 is supplied to the video signal decoding unit 624, and the compression code is decoded by the decoding method according to the present invention to obtain a baseband digital video signal. The decoded digital video signal is output after being mapped to, for example, an HD-SDI format.

  The digital demodulation unit 623 is also supplied with a digital audio signal and other signals that are digitally modulated and transmitted on the transmission unit 600 side. The digital demodulator 623 demodulates a signal obtained by digitally modulating these digital audio signals and other signals, and restores and outputs the digital audio signals and other signals.

  Further, the front end unit 622 performs error detection on the received signal supplied from the wireless module unit 621 by a predetermined method, and outputs an ARQ when an error is detected, for example, an incorrect frame is received. . The ARQ is supplied to the wireless module unit 621 and transmitted from the antenna 620.

  In such a configuration, the transmission unit 600 is incorporated in, for example, a relatively small video camera device having the video camera unit 602, a monitor device is connected to the reception device 601, and the digital video output from the video signal decoding unit 624 is connected. A signal is supplied to the monitor device. If the video camera device incorporating the transmission unit 600 is within the reach of the radio wave transmitted from the wireless module unit 612 with respect to the reception device 601, an image captured by the video camera device is reduced in delay, for example, 1 It can be viewed by the monitoring device with a delay within the field or one frame time.

  In FIG. 38, communication between the transmission unit 600 and the reception device 601 is performed using wireless communication, and a video signal is transmitted via wireless communication. However, this is limited to this example. Not. For example, the transmission unit 600 and the reception device 601 may be connected via a network such as the Internet. In this case, the wireless module unit 612 on the transmission unit 600 side and the wireless module unit 621 on the reception device 601 side are communication interfaces capable of communication using IP (Internet Protocol).

  The system according to the eighth embodiment can have various applications. For example, the system according to the eighth embodiment can be applied to a video conference system. For example, a simple video camera device capable of USB (Universal Serial Bus) connection is connected to a computer device such as a personal computer, and a video signal encoding unit 610 and a video signal decoding unit 624 are mounted on the computer device side. The video signal encoding unit 610 and the video signal decoding unit 624 mounted on the computer device may be configured by hardware, or may be realized as software that operates on the computer device.

  For example, a computer device and a video camera device connected to the computer device are prepared for each member who participates in the conference, and the computer device is wired and / or wirelessly connected to a server device that provides a service of a video conference system, for example. Connected via network. The video signal output from the video camera device is supplied to the computer device via the USB cable, and is encoded by the video signal encoding unit 610 in the computer device. The computer device transmits an encoded stream obtained by encoding a video signal to a server device or the like via a network.

  The server device transmits the received encoded stream to the computer devices of the participating members via the network. This encoded stream is received by the computer device of each participating member, and the video signal decoding unit 624 in the computer device performs the decoding process according to the present invention. The image data output from the video signal decoding unit 624 is displayed as a video on the display unit of the computer device.

  In other words, the images taken by the video camera devices of the other participating members are displayed on the display unit of the computer device of each participating member. According to the eighth embodiment of the present invention, the delay time from the encoding of a video signal by photographing with a video camera device to the decoding by another participating member's computer device is short, and the participating member's computer device It is possible to reduce the uncomfortable feeling of the images of the other participating members displayed on the display unit.

  Furthermore, it is conceivable that the video signal encoding unit 610 is mounted on the video camera device side. For example, the transmission unit 600 is built in the video camera device. With this configuration, it is not necessary to connect another device such as a computer device to the video camera device.

  Such a system including the video camera device incorporating the transmission unit 600 and the receiving device 601 may have various applications other than the above-described video conference system. For example, as schematically shown in FIG. 39, this system can be applied to a home game machine. In FIG. 39, a video camera apparatus 700 incorporates a transmission unit 600 according to the eighth embodiment of the present invention.

  The main body 701 of the home game machine is generated by, for example, a CPU, a RAM and a ROM, a disk drive device corresponding to a CD-ROM (Compact Disc-Read Only Memory) and a DVD-ROM (Digital Versatile Disc-ROM), and a CPU. The graphic control unit that converts the display control signal into a video signal and outputs it, the audio reproduction unit that reproduces the audio signal, and the like are connected by, for example, a bus, and have substantially the same configuration as the computer apparatus. The main body 701 of the consumer game device is entirely controlled by the CPU in accordance with a program stored in advance in a ROM or a program recorded in a CD-ROM or DVD-ROM loaded in a disk drive device. The RAM is used as a work memory for the CPU. A receiver 601 is built in the main body 701 of the home game machine. A digital video signal and other signals output from the receiving device 601 are supplied to the CPU via, for example, a bus.

  In such a system, for example, in the main body of a consumer game device, game software that can use an image based on a digital video signal supplied from the outside as an image in the game is activated. To do. For example, this game software can use an image based on a digital video signal supplied from the outside as an image in the game, and identifies the movement of a person (player) or the like in the image, It is possible to perform the corresponding operation.

  The video camera apparatus 700 encodes the captured digital video signal in the built-in transmission unit 600 by the video signal encoding unit 610 using the encoding method according to the present invention, and modulates the encoded stream by the digital modulation unit 611. Then, the data is supplied to the wireless module unit 612 and transmitted from the antenna 613. The transmitted radio wave is received by the antenna 620 in the receiving device 601 built in the main body 701 of the consumer game device, and the received signal is supplied to the digital demodulation unit 623 via the wireless module unit 621 and the front end unit 622. . The received signal is converted into an encoded stream demodulated by the digital demodulator 623 and supplied to the video signal decoder 624. The video signal decoding unit 624 decodes the supplied encoded stream by the decoding method according to the present invention, and outputs a baseband digital video signal.

  The baseband digital video signal output from the video signal decoding unit 624 is sent to the bus in the main body 701 of the consumer game device, and temporarily stored, for example, in the RAM. The CPU reads out the digital video signal stored in the RAM in accordance with a predetermined program so that the movement of a person in the image by the digital video signal can be detected or the image can be used in the game. To be.

  Since the delay time from when the digital video signal captured and obtained by the video camera device 700 is encoded until the encoded stream is decoded and the image is obtained by the main body 701 of the home game machine is short, the home game In the game software operating on the main body 701 of the device, the responsiveness to the movement of the player is improved, and the operability of the game can be improved.

  Note that such a video camera device 700 used with a home game machine is often configured simply from the viewpoint of price and size, and has a high processing capacity like a computer device or the like. It is assumed that CPU and memory with large storage capacity cannot be installed.

  That is, in general, the video camera device 700 is a peripheral device of the main body 701 of the home game device, which is necessary only when playing a game using the video camera device 700, and the main body 701 of the home game device. It is not a device necessary to play a game using In such a case, the video camera device 700 is often sold as a separate product from the main body 701 of the consumer game device (so-called separately sold). In that case, if the video camera device 700 is equipped with a CPU with a high processing capacity or a memory with a large storage capacity and is sold at a high price, the number of sales may generally be reduced. In that case, there is a risk that the number of games sold using the video camera device 700 may be reduced, which may lead to a decrease in profit. In particular, in home games, the penetration rate often has a strong influence on the number of sales. If the penetration rate of the video camera device 700 is low, the number of sales may be further reduced.

  Conversely, by selling a large number of video camera devices 700 at low cost and improving the penetration rate, it is possible to increase the number of sales and popularity of home video games that use this video camera device 700. Can be expected to lead to further purchase motivation of the main body 701 of the home game machine. Therefore, it is often desirable for the video camera device 700 to have a simple configuration.

  In this case, for example, it is conceivable that the video signal encoding unit 610 of the transmission unit 600 built in the video camera device 700 performs wavelet transform with a low decomposition level. By doing so, the memory capacity used for the coefficient rearranging buffer unit can be reduced.

  In addition, it is conceivable to apply the configuration of the image encoding device illustrated in FIG. 12 described in the third embodiment to the video signal encoding unit 610. Further, when the configuration of the image encoding device illustrated in FIG. 15 described in the fourth embodiment is applied to the video signal encoding unit 610, the video signal encoding unit 610 side arranges the wavelet transform coefficient data. Since it is not necessary to perform a replacement process, the burden on the video camera device 700 side can be further reduced, which is preferable. In this case, it is necessary to use the image decoding device illustrated in FIG. 16 described in the fourth embodiment as the video signal decoding unit 624 in the receiving device 601 built in the main body 701 side of the consumer game device. is there.

  In the above description, the video camera device 700 and the main body 701 of the consumer game device are described as being connected by wireless communication, but this is not limited to this example. In other words, the video camera device 700 and the main body 701 of the consumer game device may be connected to each other by an interface such as USB or IEEE1394.

  As described above, the present invention can be applied to various forms, and can be easily applied to various uses (that is, high versatility).

  The series of processes described above can be executed by hardware or can be executed by software. When a series of processing is executed by software, a program constituting the software may execute various functions by installing a computer incorporated in dedicated hardware or various programs. For example, it is installed from a program recording medium into a general-purpose personal computer or an information processing apparatus of an information processing system including a plurality of devices.

  FIG. 40 is a block diagram illustrating an example of a configuration of an information processing system that executes the above-described series of processing by a program.

  As shown in FIG. 40, an information processing system 800 includes an information processing device 801, a storage device 803 connected to the information processing device 801 by a PCI bus 802, and a plurality of video tape recorders (VTRs) VTR804- 1 to VTR804-S, a system that includes a mouse 805, a keyboard 806, and an operation controller 807 that allow a user to perform operation inputs on these. An image encoding process or image as described above can be performed by an installed program. This is a system that performs a decoding process and the like.

  For example, the information processing device 801 of the information processing system 800 stores encoded data obtained by encoding moving image content stored in a large-capacity storage device 803 configured by RAID (Redundant Arrays of Independent Disks) in the storage device 803. Or the decoded image data (moving image content) obtained by decoding the encoded data stored in the storage device 803 is stored in the storage device 803, or the encoded data or decoded image data is stored in the VTR804-1 to It can be recorded on videotape via VTR804-S. The information processing apparatus 801 is also configured to be able to take in moving image content recorded on a video tape attached to the VTR804-1 to VTR804-S into the storage device 803. At this time, the information processing apparatus 801 may encode the moving image content.

  The information processing apparatus 801 includes a microprocessor 901, a GPU (Graphics Processing Unit) 902, an XDR (Extreme Data Rate) -RAM 903, a south bridge 904, an HDD 905, a USB interface (USB I / F) 906, and a sound input / output codec 907. Have.

  The GPU 902 is connected to the microprocessor 901 via a dedicated bus 911. The XDR-RAM 903 is connected to the microprocessor 901 via a dedicated bus 912. The south bridge 904 is connected to the I / O controller 944 of the microprocessor 901 via a dedicated bus. An HDD 905, a USB interface 906, and a sound input / output codec 907 are also connected to the south bridge 904. A speaker 921 is connected to the sound input / output codec 907. A display 922 is connected to the GPU 902.

  The south bridge 904 is further connected to a mouse 805 keyboard 806, VTR804-1 to VTR804-S, a storage device 803, and an operation controller 807 via a PCI bus 802.

  The mouse 805 and the keyboard 806 receive a user operation input, and supply a signal indicating the content of the user operation input to the microprocessor 901 via the PCI bus 802 and the south bridge 904. The storage device 803 and VTR804-1 to VTR804-S can record or reproduce predetermined data.

  Further, a drive 808 is connected to the PCI bus 802 as necessary, and a removable medium 811 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory is appropriately mounted, and a computer program read from them is necessary. Is installed in the HDD 905 according to

  The microprocessor 901 includes a general-purpose main CPU core 941 that executes a basic program such as an OS (Operating System), and a plurality (in this case, eight) RISC (Reduced) connected to the main CPU core 941 via an internal bus 945. Instruction Set Computer) type signal processor, sub CPU core 942-1 to sub CPU core 942-8, for example, a memory controller 943 that performs memory control on an XDR-RAM 903 having a capacity of 256 [MByte], and a south A multi-core configuration in which an I / O (In / Out) controller 944 that manages input / output of data to / from the bridge 904 is integrated on one chip, and, for example, an operating frequency of 4 [GHz] is realized.

  The microprocessor 901 reads out a necessary application program stored in the HDD 905 based on a control program stored in the HDD 905 at the time of start-up and develops it in the XDR-RAM 903, and thereafter, based on this application program and an operator operation. Perform the necessary control processing.

  Further, the microprocessor 901 executes the software to realize, for example, the image encoding process and the image decoding process of each of the embodiments described above, and the encoded stream obtained as a result of the encoding is transmitted to the south bridge 904. Thus, the playback video of the moving image content obtained as a result of being decoded and supplied to the HDD 905 can be transferred to the GPU 902 and displayed on the display 922.

  Although the usage method of each CPU core in the microprocessor 901 is arbitrary, for example, the main CPU core 941 performs processing related to control of image encoding processing and image decoding processing, and includes eight sub CPU cores 942-1 to 942-1. Each processing such as wavelet transform, coefficient rearrangement, entropy coding, entropy decoding, inverse wavelet transform, quantization, and inverse quantization is performed on the sub CPU core 942-8, for example, as described with reference to FIG. You may make it perform simultaneously and parallelly. At this time, if the main CPU core 941 allocates processing in units of line blocks (precincts) to each of the eight sub CPU cores 942-1 to 942-8, image coding processing or The image decoding process is executed simultaneously in parallel in units of line blocks as in the case described with reference to FIG. That is, the efficiency of the image encoding process and the image decoding process can be improved, the delay time of the entire process can be shortened, and further, the load, the processing time, and the memory capacity required for the process can be reduced. Of course, each process may be performed by other methods.

  For example, a part of the eight sub CPU cores 942 to 942-8 of the microprocessor 901 can execute the encoding process and the other part can execute the decoding process simultaneously in parallel. It is.

  For example, when an independent encoder or decoder or a codec processing device is connected to the PCI bus 802, the eight sub CPU cores 942 to 942-8 of the microprocessor 901 are connected to the south bridge 904. The processing executed by these devices may be controlled via the PCI bus 802. Further, when a plurality of these devices are connected, or when these devices include a plurality of decoders or encoders, the eight sub CPU cores 942 to 942-8 of the microprocessor 901 are: Processing performed by a plurality of decoders or encoders may be shared and controlled.

  At this time, the main CPU core 941 manages the operations of the eight sub CPU cores 942 to 942-8, assigns processing to each sub CPU core, and collects processing results. Further, the main CPU core 941 performs processes other than those performed by these sub CPU cores. For example, the main CPU core 941 receives commands supplied from the mouse 805, the keyboard 806, or the operation controller 807 via the south bridge 904, and executes various processes according to the commands.

  In addition to the final rendering processing related to texture embedding when moving the playback video of the video content displayed on the display 922, the GPU 902 displays a plurality of playback videos of the video content and still images of the still image content on the display 922 at a time. It manages functions such as coordinate transformation calculation processing for display and enlargement / reduction processing for playback images of moving image content and still images of still image content, thereby reducing the processing load on the microprocessor 901.

  Under the control of the microprocessor 901, the GPU 902 performs predetermined signal processing on the supplied video data of moving image content and image data of still image content, and displays the obtained video data and image data as a result. The image signal is sent to 922, and the image signal is displayed on the display 922.

  By the way, the playback video in a plurality of video contents decoded in parallel in parallel by the eight sub CPU cores 942 to 942-8 in the microprocessor 901 is transferred to the GPU 902 via the bus 911. The transfer speed at this time is, for example, a maximum of 30 [Gbyte / sec], so that even a complex reproduced video with a special effect can be displayed at high speed and smoothly.

  Further, the microprocessor 901 performs audio mixing processing on the audio data among the video data and audio data of the moving image content, and the edited audio data obtained as a result is sent via the south bridge 904 and the sound input / output codec 907. The sound based on the sound signal can be output from the speaker 921 by sending it to the speaker 921.

  When the above-described series of processing is executed by software, a program constituting the software is installed from a network or a recording medium.

  For example, as shown in FIG. 40, this recording medium is distributed to distribute the program to the user separately from the apparatus main body, and includes a magnetic disk (including a flexible disk) on which the program is recorded, an optical disk ( CD-ROM, including DVD), magneto-optical disk (including MD), or removable media 811 made of semiconductor memory, etc., as well as being distributed to users in a pre-installed state in the device body. It is composed of an HDD 905, a storage device 803, and the like in which programs are recorded. Of course, the recording medium may be a semiconductor memory such as a ROM or a flash memory.

  In the above description, eight sub CPU cores are configured in the microprocessor 901. However, the present invention is not limited to this, and the number of sub CPU cores is arbitrary. Further, the microprocessor 901 may not be configured by a plurality of cores such as a main CPU core and a sub CPU core, and may be a CPU configured by a single core (one core). Further, a plurality of CPUs may be used instead of the microprocessor 901, or a plurality of information processing apparatuses are used (that is, a program for executing the processing of the present invention is operated in a plurality of apparatuses operating in cooperation with each other). Execute).

  In the present specification, the step of describing the program recorded on the recording medium is not limited to the processing performed in chronological order according to the described order, but is not necessarily performed in chronological order. It also includes processes that are executed individually.

  Further, in this specification, the system represents the entire apparatus constituted by a plurality of devices (apparatuses).

  In the above description, the configuration described as one device may be divided and configured as a plurality of devices. Conversely, the configurations described above as a plurality of devices may be combined into a single device. Of course, configurations other than those described above may be added to the configuration of each device. Furthermore, if the configuration and operation of the entire system are substantially the same, a part of the configuration of a certain device may be included in the configuration of another device.

  The present invention described above can be applied to various devices as long as it is an apparatus or a system that compresses and encodes an image and transmits it, and decodes and outputs the compressed code at the transmission destination. The present invention is particularly suitable for use in an apparatus or system that requires a short delay from image compression encoding to decoding and output.

  For example, the present invention is suitable for use in medical telemedicine diagnosis in which a magic hand is operated while performing a therapeutic action while watching an image taken with a video camera. The present invention is also suitable for use in compression encoding and transmission of a digital video signal and decoding of a compression encoded digital video signal in a system such as a broadcasting station.

  Furthermore, the present invention can be applied to a system that distributes live-streamed video, a system that enables interactive communication between students and teachers in an educational setting, and the like.

  Furthermore, for transmission of image data taken by a mobile terminal having an imaging function, such as a mobile phone terminal with a camera function, a system using a video conference system, a surveillance camera, and a recorder that records video taken by the surveillance camera. The present invention can be applied.

Claims (37)

An encoding device for encoding image data,
Filter means for hierarchically filtering the image data and generating a plurality of subbands composed of coefficient data decomposed for each frequency band;
Storage means for accumulatively storing coefficient data generated by the filter means;
Coding apparatus comprising: coefficient reordering means for reordering the coefficient data stored by the storage means so as to be output in a predetermined order.
2. The encoding device according to claim 1, wherein the filter means performs the filtering process in units of lines from the upper end side to the lower end side of the screen. The filter means performs a filtering process on the image data for each line block that is image data corresponding to the number of lines necessary to generate coefficient data for at least one line of subbands of the lowest frequency component. 2. The encoding device according to 2. 2. The encoding apparatus according to claim 1, wherein the filtering unit performs the filtering process in both a vertical direction and a horizontal direction of a screen corresponding to the image data. 2. The encoding device according to claim 1, wherein at least one of the number of taps and the number of decomposition levels of the filter processing by the filter unit is determined according to a target delay time. 2. The encoding apparatus according to claim 1, wherein the filter means performs wavelet filter processing that further performs the filter processing on low-band component subband coefficient data obtained by the filtering processing. 7. The encoding apparatus according to claim 6, wherein the filter means performs the wavelet filter processing using a lifting technique. The filter means, when performing the filter processing of decomposition level = X + 1 using the lifting technique, performs on the coefficient data calculated as the subband of the low frequency component by the filter processing of decomposition level = X. Item 7. The encoding device according to Item 6. The storage means
First buffer means for holding low-frequency component subband coefficient data generated in the course of the wavelet filter processing by the filter means;
7. The encoding device according to claim 6, further comprising second buffer means for holding high-frequency component subband coefficient data generated in the course of the wavelet filter processing by the filter means. 10. The second buffer means holds subband coefficient data of a component in a band other than the lowest band until the subband coefficient data of the lowest band component is generated by the filter means. Encoding device. 2. The encoding apparatus according to claim 1, wherein the coefficient rearranging unit rearranges the coefficient data so that the subbands are output in order from a low frequency component to a high frequency component. The coefficient rearranging means rearranges the image data for each line block that is image data corresponding to the number of lines necessary to generate coefficient data for at least one line of the subband of the lowest frequency component. The encoding device according to claim 1. 2. The encoding device according to claim 1, further comprising entropy encoding means for entropy encoding the coefficient data. 14. The encoding apparatus according to claim 13, wherein the entropy encoding unit sequentially entropy encodes the coefficient data rearranged by the coefficient rearranging unit. The coefficient rearranging means rearranges the coefficient data so that the subbands are output in the order of low frequency components to high frequency components,
15. The code according to claim 14, wherein the entropy encoding means entropy-encodes the rearranged coefficient data in order of low frequency components to high frequency components as soon as the coefficient data is rearranged by the coefficient rearranging means. Device. The entropy encoding means performs entropy encoding on the coefficient data generated by the filter means,
14. The encoding device according to claim 13, wherein the storage unit stores the coefficient data entropy encoded by the entropy encoding unit. The storage means is generated as subbands of band components other than the lowest band component until the coefficient data of the subband of the lowest band component is entropy coded by the entropy coding means, and the entropy coding means performs entropy coding. 17. The encoding device according to claim 16, wherein encoded coefficient data is stored. The coefficient rearranging means rearranges the coefficient data entropy-encoded by the entropy encoding means stored in the storage means so as to output the subbands in the order of low-frequency components to high-frequency components. 17. The encoding apparatus according to claim 16, wherein as soon as the coefficient data is rearranged, the rearranged coefficient data is output in the order of low frequency components to high frequency components. 14. The encoding apparatus according to claim 13, wherein the entropy encoding unit collectively entropy encodes coefficient data of a plurality of lines in the same subband. The entropy encoding means includes all sub-blocks constituting a line block that is a coefficient data group corresponding to image data for the number of lines necessary to generate coefficient data for one line of at least the subband of the lowest frequency component. 14. The encoding device according to claim 13, wherein encoding is performed on a coefficient data string in which band lines are arranged in a one-dimensional direction in order from low to high. The entropy encoding means includes
Quantization means for quantizing the coefficient data generated by the filter means;
14. The encoding apparatus according to claim 13, further comprising: information source encoding means for encoding information source coefficients of quantization results obtained by quantizing the coefficient data by the quantization means. Coefficient data for each line block, which is a set of coefficient data corresponding to image data for the number of lines required to generate coefficient data for one line of at least the subband of the lowest band component, is the entropy encoding means. Packetizing means for adding a predetermined header to the encoding result data obtained by entropy encoding in the order of low-frequency components to high-frequency components, and packetizing the header and the data body;
Sending means for sending the packet generated by the packetizing means,
The entropy encoding means, the packetizing means, and the sending means perform each process simultaneously and in parallel,
The entropy encoding means performs the entropy encoding of the coefficient data in units of the line block,
The packetizing means packetizes the encoding result data for each line block as soon as the encoding result data for each line block is generated by entropy encoding by the entropy encoding means,
14. The encoding device according to claim 13, wherein the sending means sends the obtained packet as soon as the encoding result data for each line block is packetized by the packetizing means. 23. The encoding device according to claim 22, wherein identification information for identifying the line block in the screen, a data length of a data body, and encoding information are recorded in the header. The entropy encoding means includes
Quantization means for quantizing the coefficient data generated by the filter means;
An information source encoding unit that encodes a coefficient of a quantization result obtained by quantizing the coefficient data by the quantization unit;
24. The encoding device according to claim 23, wherein the encoding information includes information on a quantization step size of quantization by the quantization means. 25. The encoding device according to claim 24, wherein the quantization step size information includes quantization step size information for every subband. An encoding method of an encoding device for encoding image data,
A filtering step for hierarchically filtering the image data and generating a plurality of subbands composed of coefficient data decomposed for each frequency band;
A storage control step of accumulatively storing the coefficient data generated by the processing of the filter step in a storage unit;
An encoding method comprising: a coefficient rearranging step for rearranging the coefficient data controlled by the processing of the storage control step and stored in the storage unit so as to be output in a predetermined order. A decoding device for decoding encoded data obtained by encoding image data,
Storage means for storing coefficient data of a plurality of subbands that are supplied in units of lines and subjected to hierarchical first filter processing on the image data and decomposed for each frequency band;
Coefficient reordering means for reordering the coefficient data stored in the storage means so as to be output in a predetermined order;
A second filtering process is performed on the coefficient data rearranged by the rearranging unit and output from the storage unit, and the coefficient data of a plurality of subbands decomposed into frequency bands are combined to generate the image. A decoding device comprising: filter means for generating data. 28. The decoding device according to claim 27, wherein the coefficient rearranging unit rearranges the coefficient data so that the subbands are output in order from a low frequency component to a high frequency component. The coefficient rearranging means converts the coefficient data stored in the storage means into image data corresponding to the number of lines necessary to generate coefficient data for at least one line of the subband of the lowest frequency component. 28. The decoding device according to claim 27, wherein rearrangement is performed for each line block that is a set of the corresponding coefficient data. 28. The decoding device according to claim 27, wherein the filter means generates the image data by performing the second filter processing in line units from the upper end side to the lower end side of the screen. The filter means is a line that is a set of the coefficient data corresponding to image data corresponding to the number of lines necessary to generate at least one line of coefficient data of the subband of the lowest frequency component with respect to the coefficient data. 28. The decoding device according to claim 27, wherein the second filter processing is performed for each block. 28. The decoding device according to claim 27, wherein the filter means performs the second filter processing using a lifting technique. Entropy decoding means for entropy decoding the encoded data in units of lines for each subband;
28. The decoding device according to claim 27, wherein the storage unit stores coefficient data obtained by entropy decoding by the entropy decoding unit. The entropy decoding means includes all subbands constituting a line block that is a coefficient data group corresponding to image data corresponding to the number of lines necessary to generate coefficient data for one line of at least one subband of the lowest frequency component. 34. The decoding device according to claim 33, wherein the encoded data in which the lines are encoded and arranged one-dimensionally is decoded. The entropy decoding means includes
Information source decoding means for performing information source decoding on the encoded data;
34. The decoding apparatus according to claim 33, further comprising: an inverse quantization unit that inversely quantizes coefficient data obtained as a result of information source decoding by the information source decoding unit. A decoding method of a decoding device for decoding encoded data obtained by encoding image data,
A storage control step of storing, in a storage unit, coefficient data of a plurality of subbands which are supplied in units of lines and subjected to first filter processing hierarchically for the image data and decomposed for each frequency band;
A coefficient rearrangement step for rearranging the coefficient data controlled by the processing of the storage control step and stored in the storage unit in a predetermined order;
A second filter process is performed on the coefficient data rearranged by the process of the rearrangement step and output from the storage unit, and a plurality of subband coefficient data decomposed into frequency bands are synthesized to generate image data. And a filtering step for generating A transmission system comprising: an encoding device that encodes image data; and a decoding device that decodes encoded data obtained by encoding the image data, and transmits the encoded data between the encoding device and the decoding device. Because
The encoding device includes:
First filter means for performing a first filtering process on the image data hierarchically, and generating a plurality of subbands composed of coefficient data decomposed for each frequency band;
Storage means for accumulatively storing the coefficient data generated by the first filter means;
Coefficient reordering means for reordering the coefficient data stored by the storage means so as to be output in a predetermined order;
The decoding device
Coefficients of a plurality of subbands decomposed into frequency bands by performing a second filter process on the coefficient data rearranged by the coefficient rearranging means transmitted from the encoding device via a transmission path. And a second filter means for generating image data by combining the data.

Images